Time limit for medicals - 4 weeks
Yep ZFWT - 4 weeks.
I learnt through experience - thought I would get everything in nice and early on my second ever medical a few years ago. When I finally got my new medical I noticed the expiry date was only about 11 months on from the previous one. Huh?? Its somewhere in the regs as I discovered from a rather pompous CASA dude who exposed my ignorance when I phoned to enquire.
And yet every year I have had to call up CASA because my new medical hasnt arrived by a day or two before my expiry date - and this despite the fact that I go see my DAME each year as close as possible to 3 weeks and 6 days prior to my expiry date.