So I was banned for three weeks and my banned is up Monday, my question is am I allowed to apply for a support ticket on Monday or do I wait till the next day?

you can send it on either day, doesnt mean they have to respond that same day about it.

I realized that (looks down kinda sad.)

If you submit to support on the final day of your ban, you will be unbanned on the same day.

Will do, thanks Erek.

Oh and what should the ticket say?

Just give your character name, possibly email and state that you are requesting your account to be reactivated as your ban period has ended. Make sure that you request the correct account to be unbanned as indicated in the Sim News about your ban as usually the ASims will only unban one specific account.

Any time during the day right?

Day? Thats vague. Our staff is from all over the world.