Transfer between Terminal 2 and 1

Hello, I arrive from a Ahmedabad via SpiceJet at 11pm at Jaipur Terminal 2 and my next flight on Etihad is departing at 3am from Terminal 1. 1) How to get from Terminal 2 to Terminal 1 at midnight? Walk, cab, shuttle bus or something else? 2) How long would it take to do the transfer? 3) I have two separate tickets and need to check in for my international flight by midnight. Do I have enough time to do this transfer?