my DS was in a grobag from about 10 or 11 weeks i think. they were fantastic for us - he never liked being wrapped so they were really handy. then as he got older & moved around more in his sleep, they stopped him from getting cold/losing his blankets etc. for 6-18 months we had a 1.0 tog & a 2.5 tog grobag to cover different weather. i thought the 6-18 months were great value because it lasted him for a year. he doesn't use one now (has just turned 2) & i actually can't remember when we stopped - probably once he grew out of the 6-18 months ones! we could have kept going & i know alot of people do, but we just stopped.

i agree with livingthedream - it's def worth keeping it to see what happens. if there's one thing i've learnt, it's that babies are completely unpredictable! and the resale value is pretty good.