I cannot remember if XFX is reputable for PSU's, wait for someone on here to confirm. Otherwise, it looks pretty good. Only wait till christmas if you think you can get a deal on some of the parts (which may be likely due to holiday sales). I would probably just buy now, your tech is not going to be latest and greatest long, so just go for it and enjoy! You can set yourself up to receive some pretty awesome games for Xmas .
scan have daily deals which involve discounting a ridiculous amount of their stock, so you may want to wait till things come up in that. When I bought my pc from them for example, by buying at a weekend i saved something like £100, a very non trivial amount.