We visited Bansko first week of March 2004 and had wonderful snow. Indeed on the Tuesday afternoon we had to stop skiing as it was snowing far too much.
Stopped skiing because there's too much snow! Buy a board, me-thinks!
Seriously, OP, you'll be well unlucky if the snows not good then. We went/are going roughly the same time. For good reason. Bansko last year at that time was bang on, and so it should be again.