Will I get a rebate if I paid for half of what I owed and signed up to pay monthly installments? If yes, When?

If you owe taxes, any amount owed will be deducted from your stimulas check. If they take it all, and you still owe, that amount will be payed through the monthly installments. If your stimulas check is more then what you owe, they will send you a check with the balance.