When to stop using warming pad and switch to grow light?

I planted these seeds on the 16th and now I'm seeing a lot of sprouts from the tomatoes. I bottom watered only once after mixing my starting soil to moisturize. I've had a warming pad on 24-7 underneath my tray with the cover on but the sprouts are starting to run into that cover.

My question is: Should I remove my pad and the cover and turn the grow-light on even if the other seeds haven't sprouted? I'm also a bit worried about some of these guys falling over, how can I help that? TIA!