It's a good thought, but let me add something... Sometimes changing the return date at pickup can incur a much higher rate than just letting the system re-rate it on return. It seems logical that the rate would be the same in both cases, but we've found that this isn't always the case. I would ask how much it would be to return early, and if it sounds good, then just have them change it on the spot. If it sounds too high, I might just tell them to leave it and then take my chances at return. At worst, it will be what the agent quoted at the counter, but it may end up being a lot better, and even if it's not, you can go inside with your contract and plead your case to the agent to have them adjust. If you're nice, and they're in a good mood, they may just be willing to override. It doesn't hurt to bring holiday treats to "motivate" the staff.