The Final Proof: Warm but Not Too Warm
Okay so, your croissants are shaped. They're sitting on the pan looking like little dough footballs, and you're probably tempted to just shove them in the oven and get on with your life. Don't. This is the step people rush and it's also the step that decides whether you get something light and layered or something dense that tastes like bread pretending.
Here's the thing about proofing laminated dough. You're trying to do two things at once that don't naturally want to happen together. You need the yeast to wake up and puff the dough. And you need the butter to stay solid enough that it doesn't just melt out into the pan before it gets its chance to steam and separate those layers in the oven. Too cold, and proofing takes forever and your croissants never get that jiggle you want. Too warm, and the butter turns to liquid, seeps out, and you lose all that lamination work from the last two weeks of lessons.
So the target is warm, but not warm like your kitchen in July. Warm like a gentle, patient warm.
What "warm enough" actually means
I aim for somewhere around 75 to 80 degrees for the proofing environment. That's it. Not hot. If you've got an oven with a proof setting, great, use it, but check the actual temperature with a thermometer first because some ovens run hotter than they say. If yours doesn't have a proof setting, here's what I do at home: turn the oven on for about a minute, turn it back off, and then put the croissants in there with the door cracked or just closed with a bowl of hot water on the rack below them. You're creating a little warm, humid pocket. Not an actual heat source.
Whatever you do, don't put them somewhere with visible heat, like right next to a heating vent or on top of the oven while something's baking below. That's a fast track to butter running everywhere.
The visual and the poke test
You're looking for the croissants to get noticeably puffier, maybe close to double in size, and when you gently poke one with a finger it should feel soft and a little jiggly, like it's got some air in there, and the indent should slowly spring back rather than staying dented or bouncing back instantly. Slowly is the key word. Instantly means it's not ready. Not springing back at all means you've gone too far and it's overproofed, which happens, no worries at all, but the structure will suffer some.
This whole process usually takes an hour and a half to two and a half hours depending on your kitchen. Dry Utah air and our elevation mess with a lot of baking assumptions, but proofing time is actually more about ambient temperature than dryness, so don't rush it just because things feel dry. Check the dough, not the clock.
The visible butter test
Here's a trick I use constantly. Hold the croissant up and look at it from the side against a light. If you can see little streaks of butter starting to look shiny or slightly translucent through the dough, that's your sign the butter is getting close to its melting point and you need to get it in the oven now, not in twenty more minutes. That visual cue has saved me more batches than I can count.
The anecdote, since we're here
My proudest single croissant, the one with something like forty visible layers when I cross-sectioned it, came out of a proof that I almost blew because I got impatient. I had it in a spot that was too warm, checked it too late, saw butter starting to shine through, and yanked it straight into a cold oven that I then cranked up. It worked, barely. When I pulled that batch and cut into the best one, I counted layers under my desk lamp like an idiot, photographed it from four different angles, and texted the photos to the ward group chat at 6 in the morning because I genuinely could not wait for a decent hour. Nobody responded until like 8:30. Didn't care. That's basically the payoff you're working toward here, that cross section, and it lives or dies on getting this proofing step right.
My opinion on this, since I've said it before about other steps
I think patience matters more than precision here too. People want an exact number, exact minutes, and I get it, but what actually matters is watching the dough instead of watching the clock. The dough will tell you what it needs if you check on it every 20 minutes or so instead of setting a timer and walking away.
A real caution
Don't leave these unattended near an actual heat source, even briefly. Butter that melts out isn't just a lamination problem, it's also a genuine smoke and mess problem in a hot oven. I learned that one with my very first laminated batch ever, smoke alarm, sleeping baby, the whole disaster. That's a story for another lesson, but the short version is: warm gently, check often, and don't trust an oven you haven't verified with a thermometer.
Before next time
Try to proof one batch at home before we bake together, even a partial batch, just so you get a feel for what "soft and jiggly" actually feels like under your own finger. That feel is something you can't really get from a description, mine included.