On the curing side if you didn't send them off to Tilthy for curing I would to wait until late August after I had trimmed the flowers off so that all the energy went into the leaves. When the leaves were a tad droopy and would snap off cleanly you could start harvesting. You would stack the hands on the lawn and cover with sack cloth. Keep the temperature as warm as a broody hen so that all the green leaves turned yellow then pretty much follow Cosmic's guideline or send them off to be cured by someone else. I used to use my attic and few big metal pans of water to control the humidity and finish up in my Mothers airing cupboard.
Great advice! Although, I am totally ignorant of where of send them, but it sounds like you've got a great contact.
I would add that by the time the flowers start showing, if you are strictly wanting pipe tobacco, you can just cut the plants down, and start a new set of plants. I can get six sets of VA plants to harvest in one season here in Alabama. You probably won't like any of the leaf above the Seco line, because it will be really harsh. I will keep some burley going and definately the cigar leaf, but for Virginias, they'll rip your throat out. IMO.
The very bottom leaf is the tastiest, going up to about six tiers of leaf.
It sounds difficult, but once you see how the leaf turns yellow and you learn to read the leaf, it's really obvious and simple.