I had ACL reconstructive surgery about a month and a half ago. When I make my return to sports at 6 months. How long will I have to wear a brace?

You don't. Studies routinely have shown that bruce wear after acl reconstruction is not needed. Athletes in contact sports typically fell more "comfortable" wearing a brace of some sort for peace of mind.
Varies. Functional knee bracing after acl reconstruction is fairly common practice for most surgeons, although it's use is decreasing the past few years.For my patients who return to cutting sports @ 5-6 months i reccommend a don-joy or breg custom brace until 9 months post-op; after that it's up to the patient whether to wear it w/ sports... Some 'like' the 'feel' of it while some think its cumbersome...