Are there any rules of thumb for tipping movers who load truck on one day and deliver on the next day?
Depends upon where you are in the United States but I've heard everything not tipping them in the case of a fairly straightforward move to up to $50 per mover if they are outstanding in terms of performance or you have an especially complex move for some reason.
In the New England area the rule of thumb seems to be that you should have some sort of beverage (i.e. water, soda, etc) on hand to offer them while they are loading and unloading the truck or packing and then once the move is complete to tip them between $20 and $50 per person.
In general though, avoid giving them a tip as a percentage of the cost of the move and give the tip directly to each person as opposed to the foreman to be split among the movers.