A few months to look normal again.
Use a rake Matt brush and be consistent with it.
I can only speak from my personal experience (my current and only GD). When she was new to the house, about 4-6 months old, 25-35lbs, she would pant pretty hard at night, and I had the same concerns.
For us it didn't develop into a problem, and she grew out of it after a few weeks, maybe a month. She's now 13 months, a lanky 55lbs, and sleeps under my bed every night, breathing easy as can be.
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Side note: I'm new to this sub, don't know how popular these are... but EVERYBODY should get a teaser wand for their GD! It's my GD's absolute favorite toy, it has lasted way longer than her other toys, and a couple 5-10min play sessions make a huge difference in her attitude/energy level the rest of the day (along with bones, sniffing games, etc). We had a few sessions early on with a trainer, and their advice to get a teaser wand was probably the most valuable thing I learned from them (and I learned a lot of valuable stuff from them).
For our we got a collar off Amazon that vibrates to deter our doodle from barking (this one: - No Harm DeterrentVibrating Control Collar https://www.amazon.com/dp/B072DS462V/ref=cm_sw_r_cp_api_i_0VXVEbBAHQNG5) After having our girl wear it during the day only for a few months, she rarely barks now, one year later. I hope that helps!