I'll do my best to answer your questions. At the very beginning, when my clinic took charge of me, I had blood work done so they would check my hormone levels. Same for my husband. They had me come on day 2 or 3 of a cycle. I guess that, especially if your cycle is not regular, they want to know what's going on with your hormones. Is it because you tend to have many cycles without ovulation, or because you have too much of this, too little of that, and so on.
I see two scenarios. If you're really irregular, maybe they'll want to put you on the pill right away so they can control your hormone levels better instead of relying partly on your body to determine the moment your IVF cycle will begin. However, they might simply want to do, like me, a check to know your hormone levels better and adjust your IVF cycle in consequence, maybe without having to control you right away with the pill during April and May.
However, one thing that you should always remember when IVF-cycling, whether you're a veteran or new at this, is "When in doubt, call your clinic!" If you want to know, just call them! I'm sure a nurse will call you back with the answer.
And don't worry sweetie... the only stupid questions are the ones you don't ask!
Take care, and lots of baby dust to you!
Sophie
Not fun when you think you have already shelled out all your dough! I am hoping that doesn't happen again! 
She will only be here for two more weeks. She was the only one (other than DH) that knew we were doing IVF. I had to have someone other than DH to talk to. She is 47 and chose not to have children. Even though she couldn’t fully understand, she always made me feel better. Of course I know I will still talk to her but it won’t be the same as walking down a hallway.