Set your timer to 16:8 for vegging.

When your plants are about half the height you wish them to finish at,
switch out 2 bulbs for the lower temperature ones and switch to 12:12 at the same time.

Now, it's homework time.

Go read everything in the first link in my signature.
(Take your time, there will be a pop quiz.)
That will answer all the rest of your questions.

Aloha,
Weezard