If this is of any use, my application process went as follows:
Phase 1 - submitted application forms mid-December last year. Received a response on 3rd Jan that I had been invited to Phase 2.
Phase 2 - attended 31st Jan (although had been given the option to go on 17th Jan; however, university commitments made it easier to go on 31st.)
Received an e-mail on 2nd February telling me I was invited to Phase 3.
Phase 3 - attended 7th March. There were people there who had had a waiting time shorter than my 5 weeks. (Not that it mattered to me in the slightest - just an observation.) Received an e-mail on the afternoon of 8th March, inviting me to Phase 4.
Phase 4 - attended 16th March (although I also knew of one person from my Phase 3 who was given a date of 23rd March.) Received a phone call on the train home three hours or so later advising me I'd been accepted.
Overall, the total time for me was just under 3 months, although I do know there are people who've done it in a shorter time - sometimes you get a shorter wait time between stages. Indeed, if I'd taken the earlier Phase 2 option, it could have been quicker for me. Hope that's of use.