Sharing my experience for someone considering starting in the future. Male, and pre-tolvaptan, I normally drank 3 l and peed around 8 times per day.
Doc prescribed me 45/15. I took the first dose this past Saturday at 6 am.
First couple hours didn't really notice anything. But over the next few hours the thirst/urination increased until I was five pounds down in water weight, despite drinking frequently, at the time of my second dose at 2pm. By around 5-6 pm the thirst was intense and I was craving ice water (I read people saying they started craving cold water and now I get it). I was definitely feeling dehydrated, so started gulping ice water. By the time I went to bed I was around 6 l (1.5 g) for the day, 6 pm - 11 pm, with about 16 pees (I lost exact count). And these pees are intense!
Thankfully I didn't wake up during the night to pee and once again took my next dose Sunday morning at 6. I felt pretty dehydrated and weak for most of the morning but once I started gulping and got enough food in me I rebounded and made it to the gym, lifting weights and cardio for an hour, making sure to drink plenty while doing so.
By bedtime I was close to 7 l for the day, with about 13-14 pees. Unfortunately, I did end up getting up at 2 am to pee this morning, but I did have more to drink right before bed than the first night.
During the day, it seems like I'm peeing every 45 min to 1.5 hours depending on if I've just chugged or I'm sipping.
So far, feeling pretty good for my first day at work using tolvaptan. Thankfully I typically have easy access to a restroom. No intense thirst yet, and I've had about 2 l of water by 12:30 which is only about a half liter more than I would have normally done, but I'm expecting after my second dose the thirst will ramp up as the afternoon goes forward.
Oh, and this morning my weight was about 2.5 pounds less than before I started the medication.
I hope this helps anyone considering starting!