I've seen enough madness surrounding whne the spawn starts, and what gets it started, moon, temp, length of daylight, wearing red jeans.....
I'll say this...tempaterature has an effect on the viability of the eggs laid, and can even have an effect on the gender of the hatching fry. That's true for just about ANY egg laying fish. Lower temps = longer incubation time, which means more time with a male guarding the nest, and vice versa. I can't remember the relationship with temp to gender, but there were several farms using to influence the gender of the "crops."
So, if temperature can affect the outcome of the spawn, then I hypothesize that there is a optimal temp. I have no way to test this, but research (different from expieriments guys!) shows it's somewhere in the low 60s.
Up here, when water temp is on the rise, approaching 60° F, I start checking my ponds. They always spawn first. Then it's shallower, warmer Lakes, finally, the bigger deep lakes. I've seen smallies on beds in Lake Ontario a full month after I've caught smallies on beds in the bays. And then I've seen largemouth on beds in late July on Chautaqua Lake. Crazy stuff. I do think temperature has a big effect, but I also think that there's a ot of other factors. Moon phase, wind, suitable, calm locations, etc. Basically all the ideal conditions have to come into alignment. There's probably a window of time around this alignment that would be the "spawn."
Anyway, that's how I think of it. Anyone that says you can predict using one parameter is lying or deluded.