I started getting stuff together at around about 30 weeks (buying pads, small toiletries etc) and had the essentials packed at around 32 weeks. I know someone who went into labour at 34 weeks so I had that in the back of my head when deciding when to pack.

However, I have been adding bits and pieces to it since then...but I had the essentials in case of emergency! I also agree that DH can be sent away to get anything I have forgotten!