Jeff,I grew up in that country and hunted snakes in MD,WV and PA for years.Timber rattlesnakes and copperheads come out of their winter dens app. May 1,sometimes later.They stay around the dens at least a month before dispersing.Now garter snakes and black rat snake will be out earlier but you shouldn't worry about them.
Dens are few and far between.They are found on south facing slopes,roughly,with rock ledges and especially rock slides.Not any rock structures will do.It has to be honey-combed below the surface so snakes can get well below the frostline but no big openings to let cold air in.There is usually water within a few hundred yards.There has to be shade but also open areas for sunning.They are never on North facing slopes.
In VA and those States North of it,I wouldn't expect to see a venomous snake before May 1 and then,only at a den if I decided to traipse through or around the rocks there.Like I said,dens are few and far between and hard to find.Now I'm not speaking about States further South.Expect them to be active when the temperature is 70 degrees and above.
Having said all that,any good leather boot 8"-10" will stop a timber rattler or copperhead and even many of the padded,cordura types will too.Actual snake boots are designed to stop the largest diamondbacks and aren't needed in that country.
With standard boots,or any for that matter,you have to use common sense and not step close to a rock or other structure where a snake could strike from and hit you above the boot.
Even when wearing snake boots,one needs to be aware of his surroundings,never placing hands or feet where a snake could be hidden.How many people who feel the need to wear snake boots,really want to be surprised by a snake hitting the boot? I suspect not many.Just being startled could cause one to fall,possibly even into another snake.
Anyway,in VA,during Spring turkey season I think your risk is very low and good comfortable hunting boots will suffice,given the snakes in your area.