What is the earliest you can go
for your medical. I haven’t been sent
the forms yet. Birthday is in July.
I’m just doing mine for my card , I’m 48 but card expires on 29/4/2024 ,
There’s a bit on the general form that says “if you sent us a D4 form in the last 12 months don’t send a new one “
My work mate sent he’s in 3 months early and got it done ok .
So I would order the forms and get it done as we know how slow DVLA can be 
It seems forms are sent out 56 days before renewal is due, but you can order them at any time. Or from some Post Offices
I can’t see any “earliest application date”.
If you apply in time, and there are no peculiar circumstances, then even if DVLA are slow, you might be able to drive (UK only) for up to a year anyway. https://assets.publishing.service.gov.uk/media/64edcf3a13ae1500116e2f5d/inf1886-can-i-drive-while-my-application-is-with-dvla.pdf
Age related medical becomes due 56days before 45th birthday.
The D4 is valid for 4months from the date it is signed and dated by the Dr.
So, with a renewal in July about now-ish is the earliest a medical could be done.
Once it’s completed, your medical is valid for four months. It’s smart to get it squared away earlier and there’s no need to wait until DVLA send your forms out.
In Gateshead there’s a training provider who have a doctor visit their site twice a month (one Thursday evening, one Saturday morning). You just need to book a medical slot and turn up, they keep the forms in stock, you fill them in while waiting for the doctor, their staff do a quick check to make sure everything is kosher, see the doctor, then hand the forms over to the admin person and they send all the forms off recorded delivery. Nice and convenient
I don’t believe this is the case actually. If your 5 licence runs out within 56 days of turning 45, then a medical is due by the expiry date on the card. If your 5 year licence runs on until you are say 47, all good, your medical will be due before the expiry on your card.
One thing to note is that if you send your D4 and renewal form away early, DVLA will process it and your expiry date is not preserved in this case. Worth noting if you are paying yourself and don’t want to lose a few weeks.
Another thing to note is that if you have provisional bus and the expiry date is different to your lorry expiry, DVLA will send your forms out for the bus renewal. Your lorry renewal may be due later. When you pass your LGV you do get a new 5 years from the date of the pass, but not for the bus provisional.
You may well be correct.
I certainly am open to being wrong in my post.
It’s all good, 45 is possibly more recent to me than you. Runs to hide.
I have already entered the “twilight zone” of annual checks!
Thank you everyone who answered 
He is correct as my photo card expired in the 29/4/2019 and came back with 5 years on it so I didn’t do a medical in July 2020 for my 45th
Just done one now as my card expires 29/4/2024 and I’m only 48
Goes from photo card expiration date now