Erkin,
From what I have gathered in my research into the same subject, your incentive pay will vary. As I understand it, you will get a monthly incentive that is dependant upon your specialty. This is on top of your base pay, of course (which for a Captain, or O-3, will be probably around $3700 per month) and your food and housing allowances. The food allowance is a flat rate the is around $150 a month and housing depends on where you live but should be around $900.
As I understand it, while repaying your scholarship you are not entitled to any of the "stay in" incentives and are only eligible for the specialty incentives. The base pay will only go up as lobbyist continue to pressure Congress to close the pay gap between military and civilian people. The housing allowance is based on the cost of living so that will vary greatly. I hope this helps, their really is no way of predicting exactly what you will make at that time.
Ben