my first PG i packed it around 34 weeks, second PG i only packed it at 37 weeks. I told my friend not to bother packing hers til 36 weeks and she had the baby the week before so had nothing!!
i have 3 bags- one for the labour (small bag with sweets, hair grips, camera, etc)
one bag for after- nighties, towel, breast pads, maternity pads (not all hospitals provide these, mine didnt), arnica, slippers, dressing gown, cant remember what else
third bag for baby!- gro's, vests, cotton wool, nappies as again my hospital only provided some but as i was in for a few days they told me i would need to get DH to bring our own supply in.