Kangoo Van Aux Belt Chirping

Hi there.

I have a 51 plate Renault Kangoo 1.9D Van.

I have recently had a new battery, alternator and belt put on. It's been on several weeks now and the belt has started chirping when it starts and squeals as I pull off, but pretty much every time, by the time I'm in to second gear it's stopped. On tick over occasionally I hear a slight chirp.

I kind of expected the belt to stretch a little, and have read different stories that I should loosen the alternator and take the slack off that way, and other people saying to loosen the tensioner and take the slack off there..

Is there a preferred or better way to do it? And am I right in thinking that the belt just needs to move up and down very slightly... ?

Thanks in advance

Duncan