Just remember that the fish start into a pre-spawn mode based in great part on length of daylight . You can catch males and females moving in and out,and different year classes of fish,at different times.Some years I catch more in the prespawn then I do on beds...some years the bed fishing is better.Course if you can't go at will then how the weather and work schedules and personal stuff gets in the way effects that . Typically the surface temps I see when I am actually catching fish on the beds is 68 to 78 or so with 70 to 75 being the norm. But I have already caught redear in three feet of water in the low to mid 50's this year. But they weren't there to even fan a bed yet....they were there feeding because the shallow water had warmed more than the deeper water and they moved up for awhile. Here in this geographic latitude of lower Missouri as far as I'm concerned starting in February and ending sometime in May or the first of June fish of nearly all species are in some stage of reacting to the urge to spawn. And I am going to fish every day I can,I'm just going to vary my technique and approach and presentation. For truly bed fishing where I am trying to catch a female that is waiting to lay her eggs or a male guarding it or both...Late April to Late May around 70 - 75 degree surface temps. It doesn't all happen at once.But some years the whole thing is short and other years longer.Everything South of here a few weeks earlier,North a little later.