I fish frogs alot in the summer. I would like to know from you frog guys when you start to throw your frogs,in the early spring, pre or post spawn?

As soon as the cover dictates throwing a frog.  I'm sure you could do just as well as water temps get warm enough for any topwater, but I generally start throwing frogs when the pads start to emerge, and the weeds reach "mid slop."

Frogs should be very effective when lily pad starts to appear in the early summer.

generally around the time the lilly pads start to come up.  However, as soon as the milfoil and hydrilla get within 2 feet of the surface, Ill start throwing frogs, even if there are no pads to be seen.

I like the Spro Dean Rojas line (I'll also trim the rubber leg skirts back and bend the twin hooks upward) or the SK Rage Toad w/ 5/0 Gama Superline EWG on 65# braid.

I'll throw a frog anytime there is green vegetation near the surface. I haven't noticed a pattern with temp or sky conditions. If it looks fishy - it probably is. If they are missing a lot, I'll try to flip a weighted worm or creature bait in the hole or near the edge. 

Even if the grass is not on the surface yet, you can get the fish to come up and eat a frog or toad.  Keep your eyes open for fish feeding on the surface, this is the sign that you can catch something on top.