I would say it wasn't until after the honeymoon phase of being new and excited wore off and I was given meaningful work to complete. It was a while ago now, but I think it was around the 6-8 week mark that I begun to really notice my workdays were a waste. Being a male I suppressed my feelings :) and the stress slowly built up over the next 6 months until my wife finally pointed out that it wasn't healthy and was impacting my relationship with her and others in my life.
I'm somewhat rare in the sense that I just quit vs lining up a new job first as we had a decent financial buffer, although if I'm being honest I suspect it was a case of jumping before being pushed as the stress was starting to impact my workplace relationships as well (especially with the CEO who was a chronic time-waster that loved pointless meetings).
I've said this elsewhere, but I think it's healthy to mix things up every few years - leaving this company ultimately worked out well for me as I quickly found a new opportunity that opened up doors I had never considered before. I don't know your exact circumstances, but if you have a significant other I think it's worth having a candid conversation with them and work out what the two of you need to live a balanced and fulfilled life. If the workplace stress is leaking into the rest of your life and you find work consuming an unreasonbale amount of your time, it's probably a good sign that it might be worth exploring other opportunities (in my experience, it's much harder to change an organization than it is to just move on). I realize this is different to the "roll-up-your-sleeves" advice elsewhere in this thread, but I view my career as a 40+ year marathon so I embrace the odd twist in the road every now and again.