I would also only keep 3 running on the 1000w while you're trying to set it up if that's the only PSU you're using. Seems like very little for 4 and everything else that needs power, I could be wrong though.
Yes, I anticipated that it could cause some problems so I have another one ready to be plugged in if it is too much strain for the 1000W PSU, should have gone with the 1200 but it was not in stock friday night and I was eager to get started!