You should really have enough time for the connection all being well, just make sure you connect airside, the busses between T5 and T3 are frequent and relatively quick and security is less bad than it used to be a few months ago. If for any reason you miss the next flight (e.g. significant delay on the IB flight) just go to the desk representing AY at T3 - they will reaccommodate you, typically on the same or next day and provide accommodation if need be.