When to tell husband

I just found out I’m pregnant. My period was due on Saturday (April 30) so I’m not even four weeks yet. It was not planned so I am very nervous but also excited. My husband has previously told me that he’d want me to surprise him whenever we did get pregnant (we planned to TTC starting around the end of this year). My question is, when should I tell him? He is getting his master’s degree in CS has finals until May 10. Even though he does want a baby, this is a little earlier than we planned and I don’t want to stress him out right before all his projects and exams are due. So should I tell him now? Or wait until after may 10? Or even like a week after may 10 so he has a week to like decompress after the stress of finals? He’s been telling me how much he can’t wait until this semester is over and just be able to decompress and do nothing for a bit. I’m going to my midwife next week so I figured I’d wait until at least after that.