Most of your complaints are because you will be under probation..
Putting OT issue aside, how keen would you be to join this company?
Fresh grad with 3.7K offer is not a bad deal, the car loan issue is your own commitment.
You mention MNC.. if you confident and want to wait .. or throw the ball to MNC, tell them I cannot wait 2 weeks

Lastly, think bigger and beyond, which company gives you more mileage and looks better in your cv. you will probably not stay here forever so it is a stepping stone for your career.