Agreed EZY_FR. I suspect that the assessments will be a simple pass or fail, meaning they could potentially let us know the following day. CTC did this after our FTO assessment. We were told the next day whether or not we'd met an initial standard, the further three week or so wait was to see if we'd been called forward to Waterside (presumably based primarily on our interview performance).
If this were the case however, the earlier slots would of course gain an unfair advantage with regards to preparation time for the interview... so who knows!