I have very recent experience of this - mine was removed on Wednesday.
Mine first acted up when I was pregnant ; around 24 weeks I woke up with agonising stomach pain. Worst pain I'd felt. Waited an hour or two but it went nowhere so we eventually phoned NHS who (because I was pregnant) called an ambulance. Taken in to maternity, baby fine, scan done - no gallstones found, apparently. Sent home.
Nothing happened until 4 weeks post birth, I get another, worse, longer attack. I was fairly sure it was my gallbladder (thanks to Dr Google) and ended up waiting until the following morning to see my GP - old school doc who immediately recognised what it was, did some blood tests as he suspected I had a stone stuck in my bile duct. Called back next day to say liver results were off, redid tests following day. Same again - told to present at hospital for urgent ultrasound. That ended up being a wasted day, but the following day I was called in and had ultrasound and MRI which both confirmed that I had a crapload of gallstones (i.e. no fucking way was that earlier scan clear) and I was put on the waiting list but told it would be bumped up if the pain was becoming unmanageable.
Two days later, another attack. After it had gone on for 5 hours with tramadol making no dent, we eventually want to A&E. I was sobbing with the pain, truly awful - the A&E receptionist took one look and put me straight to triage and I was on the surgical assessment ward within 20 minutes of arriving, I must have looked horrific! Given oramorph, then soon after IV morph. By that point the attack had gone on for 6 hours and I pretty much passed out as soon as the drugs hit.
Consultant came round (this was the Sunday morning) and said as the pain was unmanageable he was bumping me up to semi-emergency surgery to be done Wednesday. Sent home with bottle of morphine. Had another attack on the Monday night which passed just as we approached the hospital.
So my experience is definitely that once it starts acting up, it gets worse and more frequent - I went from a 5 month gap, to 6 days, to 2 days. Mine wasn't triggered by any particular foods as far as I could tell either. My liver was struggling too - I had the massively discoloured urine that they tell you to watch for, in additional to bad blood tests.
Had surgery on Wednesday and it was done as day case - managed to get home Wednesday night. The surgery was honestly fine, I was sore for a couple of days but I've not had any painkillers for the last day or two and I'm up and about. I'm breastfeeding and apart from it being occasionally sore for the first day or two even that's been fine. It was done as keyhole surgery, so I have 4 roughly 1" long wounds rather than anything bigger.
I had another attack a couple of days after surgery which I think was most likely an escaped stone (I believe this can happen) but nothing since so I'm hoping it's gone now.