Hi no problems...after the medical I think it was around 5 days when I got the call and the job offer...I had my medical on a Thursday and I think they called me around the Tuesday of the next week. They then post you the orientation pack in the mail within a couple of days and within that pack is your contract which you read over, sign and post back to them. The first aid course, I'm not sure to be honest. I assume you will need to have completed this by the time you sign your contract...or perhaps by the time your ground school starts? Just do it as soon as you can and then it's done...it's an easy course.
Hope that helps!