Passing the assessment day is the minimum requirement. Flight ops management then asses the applicants in order of suitability. Based on rated/ none rated, current experience , uk licence , currency and training costs.
If you manage to tick all these boxes, then it’s usually a month or so to be offered a course. Otherwise it depends on who has joined the pool afterwards.
Some guys never get an answer, despite having passed the assessment day and met the benchmark requirements.
Dont forget, the guys n gals doing the assessment are not the ones who make the decisions . Its still the same old HR , and ultimately the most cost effective candidate will usually be successful.