The later, the better.
Apple has a really difficult set of choices. 5av, 5a, 5v, 5a and v. Is there going to be a converged 5 or one for GSM and one for CDMA. It seems unlikely that the carriers will converge on LTE within the 4G time-frame.
The earlier the 5, the less chance that it will support 4G and the less justification for anyone to buy it.
It seems unlikely that AT&T, or even Verizon, will have any significant 4G coverage in 2011. Again, the later, the more likely anything is to work. Apple leads on design but is usually conservative on technology outside their control.
Hopefully Apple will pull a rabbit out of a hat, a solution to this that is creative and surprising. However, it is not an easy problem.