... ...
You don’t need perfect books to switch from Excel to software for your bookkeeping. You need enough reliable information to be ready for the handoff: usable starting data, supporting records to verify the data, and a clean switchover date you can manage.
With those three parts in place, you can switch confidently, then improve the rest over time in a more stable system.
Being ready doesn’t mean having a perfect spreadsheet. It means establishing a reliable starting point so you can get going in your choice of software without a huge delay.
To be ready enough for a switch, you need to have three main components in place:

The plan isn’t to recreate the entire spreadsheet inside the software, so it doesn’t need to be immaculate.
You won’t be moving Excel formatting, formulas or reports into the software.
You will be using opening balances and account categories for your chart of accounts.
If your Excel bookkeeping is too messy to rely on, you have the option of redoing your current year reconciliations in the software.
The starting or opening balances are known as conversion balances. They are taken from the closing balances from the day before.
Conversion balances provide a continuation of your business totals even though the underlying transactions aren’t in the software.
These totals are usually found in account category totals on a trial balance, a balance sheet, an income statement (profit and loss report).
In your software, connect your banks and select the date from which to bring in transactions (you can go back several months if you are going to reconcile historical income and expenses). Next, focus on your account category names and your starting balances.
Bring over account categories you are familiar with but tidy them up first:
Your software has an existing and editable chart of accounts (rename/delete/add new) which you can build out using your spreadsheet categories as a reference.
Or develop a fresh categories list in a new Excel sheet. This can be converted into a CSV document to be imported directly into the software using their instructions, like these from Xero.
A CSV snapshot of account categories including account balances which can also be imported at the same time.Get these from your category totals, balance sheet or documents:
Here are pathways to help you decide:
Your start date is the start of your financial year
There is no need for income and expense history or income and expense opening balances (you are only focusing on balance sheet balances)
Your start date is the start of financial year, but it is now several months into the year
Enter current opening balances for the income and expenses (off your reconciled Excel books), or if your Excel is too messy to get reliable balances, bring in the income and expense transactions from the start of the financial year to current date and reconcile those transactions (this is a more time-consuming option)
Transactions are missing because your bank feeds started later than expected
Import the missing transactions
Don’t get trapped into thinking you have to fix your entire spreadsheet before you are allowed to upgrade.
Don’t waste costly time trying to sort things that have no bearing on your actual numbers.
Ignore messy formatting or clunky formulas that you ‘always meant to update’.
Archive your arbitrary scratch calculations or rough planning and forecasting ideas, or old and messy data from prior years.
If you will rely heavily on your Excel balances to start your software, the following should be finalized:
Finally, if you will import a CSV Chart of Accounts to the software, make sure there are no missing details. Here is a helpful article by QuickBooks.
...if you have good reason to:
Choosing a firm date to switch gives you one system to maintain (the software) and the other one to archive and use as a reference (Excel).
The date will either be:
The goal: from the switch date, you will no longer categorize and reconcile transactions in Excel, but only in the software.
In bookkeeping ‘clean’ cutoff dates usually start on the first day of a month or after a finalized tax cycle.
The start of the new financial year: this can be the simplest switchover date because you usually only need opening balances. Example, January 1
The first day of a month during the financial year: this may work better if it’s in a quieter season giving you more time to action the change. Example, March 1
The first day of a new sales tax cycle: this prevents you having to deal with split reporting from two different systems in a cycle.
These clean dates make reporting and reconciliation simpler.

You can change to software whenever it suits you, there are no rules about it, but it is good to identify a quieter period and avoid switching:
These records are used to verify balances and starting data in your new system. Keep them in an organized filing system – open a ‘Switchover’ file for that date.
Gather these source documents to support the opening balances and details covering the date your new software starts:

For the history of transactions you are importing, you don’t need to have receipts for every small purchase (like coffee), but you should have receipts or invoices for large purchases and assets (equipment or vehicles), important travel and meals, and anything you think can be questioned later.
You probably have these already somewhere in your bookkeeping filing system.
If relevant, gather:
If you can answer these questions, you are ready-enough to move.
Wait if you answer no to any of the questions above, and if:
You don’t need to hold back use of bookkeeping software whilst sorting your Excel history.
Set your switch date, open a digital folder for switch-related documents, connect your banks and select your start date for the bank feeds.
Then you can start categorizing/reconciling transactions imported automatically via bank feed.
After that, fix up anything that requires it over time:
Do I need to reconcile every past transaction before I switch?
No. You can switch, then reconcile the past, then update changed opening balances in the software (which can be done up until you run your first reports). Reconciling Excel may not be necessary at all if you plan to import current year transactions to reconcile in the software.
Should I move all my spreadsheet history into the new software?
No. Opening/conversion balances are enough for the switch.
Is it better to switch at month-end or year-end?
Month start is simplest. Year start is clean if you are not under deadline pressure.
What if my categories in Excel are inconsistent?
Pick a simple set now and commit. You can refine the categories later once the system is stable.
Can I keep using Excel for some parts of bookkeeping after I switch?
Yes, for planning and analysis. Just do not let Excel remain the system of record for transactions.