You should know with in the first few moments after introducing the female into the males cage. The act usually happens immediately, veileds aren't shy. It may last for up too 15 mins or so. The female will let the male know when she is no longer receptive.
And here is a very non-receptive female. Same animal just a half hour later! https://www.chameleonforums.com/attachment.php?attachmentid=83308&stc=1&d=1375233505
You can also try to let let some cali-worms or phoenix pupate and hatch into flies. Sometimes in the store you can find them already hatched. Just something that has worked for me. Flying insects seem to really get a cham's attention!
I use 5 gallon buckets filled about 3/4 of the way with moist beach sand. Moist not wet. You want it moist enough so that she can dig a good tunnel without it caving in on here. It could take all day, it could take a few days. I just put the bucket in her enclosure on the bottom, with a stick or...
Captive female veileds become receptive to mating at very early age. I'm talking from 3.5 to 5 months of age! You don't want her to get egg bound. Set her up in a laying bin and let her dig dig dig. See what happens.
Give Hissers a try, my guys love them, and they're easy. They can climb any thing though. They don't have any wings so my wife thinks they are beetles. He he he.:D
My Veileds usually take 2-3 days for a complete shed. Thats from when I first notice them just about to start peeling, till all the little parts, hands, feet, tip of tail are all free of the old skin. Don't freak out if you see your veiled eating his skin. that's normal.