It's hard to remember. It was a good 8 weeks of pain, but I had complications that necessitated a second surgery, and really stressed my system badly.
I finally started sleeping a bit better after 8 weeks.
I think it was 4 - 5 months til I really didn't notice it much when sleeping on my chest.
A year later, more integration.
I am now 18 months or so out, and my muscles in my body feel like they are finally letting go more. (I have narrow ribcage, and had large large ones, so my muscles have a big change to process).
Swimming in a pool, once I could do it, has really helped with the muscles adjusting (this is fairly recent, I live in an apt. complex with a pool now).
Time seemed so slow those first weeks after surgery, with the pain. I would keep taking what you need to deal, being in pain can keep you from sleep, and sleep really helps.
Good luck.
Joseph