One of the most important decisions you must make is the Starting Date for converting to Sage 50. It must be a date on which you know all account balances, customer balances, vendor balances, and so on. If possible, the start date should be the end of the previous fiscal year. If you want reports comparing this year to last year, the starting date could be the end of the previous year. You can easily enter balances from last year at any time, if you have Beginning Balance password rights.
One special feature of Sage 50 is that you can have two years open at once (up to 26 periods). That means you can keep last year's records open. It also gives you a lot of flexibility as to when you convert. For example, you can set the first accounting period to the first period of your fiscal year. This will make next year's closing easier to manage.
Next, you must decide how often you want financial statements. Keep in mind you can have from 1 to 13 periods in the fiscal year.