Figs in Zone 7/8...

I've had several Brown Turkeys over the years...they do hang in there..
It is good that you transitioned them into larger pots before plnting in ground.
It all depends on your particular microclimate though.
Do you tend to have late frosts and/or particularly damp to freezing Fall seasons.
I was probably considered cold Zone 8 and the Fig never really grew it just sort of stayed the same. What growth it made in summer would get frozen or damp rot off by end of winter.
So plant in the warmest most protected spot you have - our cold-hardy figs don't like windy spots to well either.

So for the first few years after planting I would pile straw en-masse on the tree from late fall to insulate it but still breathe.

Iyou are lucky enough to plant in front of a wall or fence you could try tacking reflective mylar behind the tree for extra solar reflection to the tree.

As always good drainage is key if your soil is clay - Which would mean much soil amendment around the the tree root zone say a yard circular ideally.
I've also had good luck with a surface mulch of contrasting black & white stuff to get extra heat adsorption (Black heats the soil & white reflects upwards).

No experience with peculiarities of Celeste. Bear in Mind they are all of a mediteranean climate. Which means it likes heat but can handle dry cold very well.
Its the damp in dormant season that gets it.