Andyva, that's exactly when we turn out the bull,.. but have never used the tomato logic. Neighbor across the river has much better sun than we do, he calves out starting Feb 4th.
My cows like holding on to them a little longer, a May 25th turnout means my first calves will hit around Mar 10th.. I have one I bred May 12th and she's about to pop, but may still hold on to it for 6 days or so if she's stubborn.
I would have been very happy to calve out all Feb this year, minimal mud and beautiful weather.. lets see what March has for us.
I've given up on breeding the heifers earlier than the cows.. it just means I have a longer calving season.. With decent nutrition I've found they all breed back with the cows anyhow, and they've grown a little in that time.. They calf in warmer weather, and when I have cows I can get colostrum from if I need it.