Not all bass spawn at the same time. If I had to guess I would say the spawn will be over a period of 8 weeks or longer. Smallmouth will go a tad earlier than LM and KY's are more in line with the LM spawn. Another thing I have noticed over the years is the larger females go earlier than the smaller females. It takes several weeks for all of them to do their thing. I caught a smallmouth one time the last week in March and she was definitely spawning based on the shape she was in. I have also caught a largemouth the last week in May and it was definitely spawning. Hence the reason I say it is a several weeks or couple month ordeal so you always have bass in different stage of the spawn late March to early June.
Now with that being said I do think there is a peak period and in my opinion it is the last week of April to the middle of May. In my opinion we are currently in the tail end of the spawn in south central KY but there is a very few late ones still to go. You have the ones that went early and hung around for a couple weeks. They are the ones that are heading for deeper water with this current warm trend. Then you have the ones that are still shallow doing their thing or just got through doing their thing. Long story short you have fish in all stages right now. They could be anywhere and caught various different ways when you find one willing to bite.
I know that is not a definitive answer but when you talking bass spawn it's a progression of weeks in different stages so there is no real definitive answer.