Yeah I try to "knead" the patch a little with my fingers while it dries. I just keep pressing anywhere that looks like it might be a potential place for air to leak (like around the edges) and eventually the thinner parts of the patch start to look kinda translucent as it vulcanizes with the rubber underneath. Then, if I don't trust it, I might put a little more "glue" on top of the edges to make sure the patch vulcanizes...but if you do this you really really have to make sure it dries or else the tube could get vulcanized to the tire.

I use the patches they sell at the dollar store (with orange tapered patches for bicycles, not the ones for cars), even though they're probably the "wrong ones" because I figure if you can't do it with readily available materials then why bother? Heck, with the "right materials" you could brew your own tubes whole, so if you're gonna get the special special formula from the special special brand then why sell yourself short at just patching?