I used to sterilise everything at the same time and then put the baby bottles in the fridge and let the breast pump parts air dry. But because I took my breast pump to work, I thought it would be better to make sure it was dry before putting it in a plastic bag and then keeping it in the office at room temperature.

If you are using the pump only at home, I don't see any reason why you shouldn't put the parts in the fridge, sealed in a clean plastic bag, until you are ready to use them.

I sterlised my LO's bottles until he was a bit over a year old, but this was mainly because we were using Dr Brown's bottles and it wasn't easy to clean the central tube, so I thought it would be safer to keep on sterilsing after the first 6 months (although by the time he could crawl he was putting everything in his mouth including his shoes).