Bought the software, done the training, that's the easy part. Before that happens you have you gather all the information your system needs to give you the information you need back out in a report. You have to think about the following and do you have all this data and if not where can you get it and who is going to get it (blatant promotion, we can help!);
Areas, Reps, Buyer Contact details, proper customer names, price lists, vies details, expemption certificates, credit rating, credit limit
price lists, proper supplier names, contact details (accounst and rep contact), intratstat details, vat number, billing addresses, delivery addresses, credit limit
Your item code and description, suppliers item code and description, intratstat details, vat number, agreed prices
This is just some of the stuff needed. Things you never thought about or the accuracy of what you have right now, all this needs to be checked and verified.
If you don't do this work, then changing your accounts system will only leave you where you currently are in accounts systems terms. But you will be grealty out of pocket and asking yourself why did you change your accounts system?