Officially, it takes up to two weeks to review and test your channel. However as the process usually involves multiple rounds of testing, reporting bugs back to the developer, waiting for the developer to fix the bugs and resubmit, reviewing and testing again, repeated until the channel meets a level we are comfortable publishing, this can be a prolonged process. So really, how many bugs in your code, how many graphics that are not up to spec or the wrong size, how many typos and textual errors in your descriptions, these are the determining factor. Some channels take 2-3 days, we probably have one or two that have been in the queue for 6 months or longer if the developer takes their time fixing issues.
You can set a desired publication date in a field that displays after you hit "Submit", and we will, within reason, attempt to get your channel published by that date if you can resolve all or most of the issues in a timely manner.