I am making an assumption that the fiscal year is a calendar based year for my answer. If it is not, adjust acccordingly, but the principles remain the same.
1. You must load in the ending (final)balance sheet amounts) in SAP as of December 31. No P&L accounts are included. Once you have loaded the amounts, then you can do the standard balance carry forward process in SAP so you have the starting balances of your current fiscal year.
2. Load the monthly activity month-by-month for January through April (assumption: April is the last month for processing financials in the legacy system. Avoid trying to load in every transaction processed this year in teh legacy system into SAP. It is difficult and time consuming and, depending on the number of company codes/accounts, the reconcilation process can take a very long time.
3. When reconciling the financial statement balances in SAP against legacy financial statements, I like to balance the monthly activity first and then the YTD.
4. Dealing with sub-ledgers, such as A/P, A/R and Fixed Assets: For A/P, whenever possible, try to have A/P cut as many checks for the final cutover (this would be for April data conversion) to minimize the number of A/P open items you must convert. For all of the subledgers, you will need a conversion account. Remember in SAP, the A/R, A/P reconcilation accounts cannot be posted to direclty, so you will need conversion accounts. These are one time use accounts for the conversion only and once conversion is finished, they should be blocked for posting an never used again. For Fixed Assets, you need to work with your Fixed Asset person as FA has a unique way of loading Asset Masters/Historical values/Accumulated Depreciation
This is just a short list of items to consider just focusing on FI area. For P&L accounts, your conversion in the current year will be a bit difficult as you also want to populate the related CO object (like cost center) or if you are using project systems, dealing with projects in flight, wehre part of the costs is is the legacy system and new costs in SAP.
