I think you're doing a good job. Sounds like you've done your homework and that you have your stuff pretty well dialed in.

Once your seedlings hit their third node they are no longer seedlings and you can put them into the tent. Bring that T5 down a 5" / day until it is 5" - 8" off the plants. That will get them ready for the MH juice. When they go into veg keep that light has high up as you can and move down a foot / day so that they aren't shocked by the sudden increase in photons.

Some people swear by the heating pad under their seedlings. From what I've read you want to keep the temps down below 68 and you need to keep a close eye on the water as they dry out quickly. Said to promote root growth.

Nutes can go on 1/4 strength every 3rd watering after the 3rd node. Note, do not start under the MH light and Nutes at the same time. Let them adjust to the nutes or light for a few days before starting the other. Bring you nutes up to 1/2 strength after 2 weeks. Careful not to over water.

Think about your re-potting schedule. Once before they go to veg or just after and once before they go to flower or just after. Again, do not coincide re-potting with additional nutes or move to new lighting or lighting schedule.

Post up some piccies. We'll be watching.