What's the earliest you can move house bunnies outside ?

Have Had two house bunnies for a year indoors (they were previously both outdoor bunnies back in the day )
I'm thinking of moving them outdoors at a new house to a decent sized shed (with a secure door and concrete floor
(Thinking about putting plastic corrugated down on top of the concrete (as that's what they had in their bunny room whilst indoors)
Feels like the temperature goes down to 3C overnight currently
So not sure how that would be in a non insulated wooden shed for them even with plenty of hay , each other to snuggle up to and maybe some P@H heatpads ??
I might be able to keep them indoors for a month, before we put down new carpet in the new house
Need to bunny proof the garden too . Rabbits need to leave their current indoor accommodation next
week and not sure if the two respective rescues (BARC or RSPCA) would take them back to rehome them together ?

Any help gratefully received , they are a lovely couple

I would not put indoor Rabbits to live outdoors when atmospheric temperatures still dropped below 10c. So I would not put them out until the end of April at the earliest. Not even then if the overnight temperatures remained below 10c

I'm in the same position. They WERE outside until Christmas, when I had to bring them in for health reasons. Unfortunately letting agents say they want them back out by ... well, now really. I think it's too cold it's droppign to around 0 at the moment, i think when it gets to around 5 at night i will be happy to put them outdoors.