Hello, and welcome on the forum.
Are you sure the tubes have been sleeping ever since??
If they have been used in between, there is nothing special to do.
If yes, here are the instructions, just scroll down.
http://www.jacmusic.com/avvt/index.htmFor better navigation you should go there via the jacmusic site.
AVVT 302B is a very good tube. It draws very much heater current,
so make your you have the 5V as required. Some people underheat
them unknowing.
This is not a 300B. It biases like a 300B, but heater current is 2x higher,
and so is peak emission. Be careful, you need a relatively low grid
resistor like 50k.
Jac