Just some follow-up on my first post. I located one of our Boxer books...this one is written by Stephanie Abraham. She says, "ears are cropped most commonly when the puppy is between six and twelve weeks old." I'm certain that there are some vets who may do it later than that BUT should you choose to crop, I suggest getting pictures of other dogs ears that have been done and asking a whole lot of questions. Find out what the care involves, who will be expected to do it (most likely, you), etc. As far as the docking of tails is concerned, she says, "docking is carried out when puppies are only a few days old."
Granted, some people are going to give different time lines for these procedures to be carried out but this information is according to a woman who, along with her husband, has been breeding boxers since 1970. She also serves as a judge of the breed during competitions. She may even sit on the BOD of the ABC (this I haven't confirmed but remember hearing about it). This is just me, but I'd take her word for it.
I'm certain others will have something to say about this but, I believe, the consensus is for docking to be done within a few days of birth and for cropping to be done before 12 weeks. Whatever you do, please do some research via this site....there is a wealth of information at your fingertips.