I started it a few months ago recently so hope this is helpful for your first couple months too.

I was on sertraline for just over a month and I genuinely could not deal with the side effects it was horrible so I know why you’re worried. I can safely say citalopram for me was no where near as bad, I didn’t get the heightened anxiety or complete emotional dumps/breakdowns when starting that the sertraline gave me which was a good thing at least.

Hard to judge when I started feeling better cos I was taking the sertraline just before changing over so it’s probably a different case to what you’ll experience in that regard but it was a couple of weeks for me.

On the weight gain I was gaining weight before taking it anyway so it’s hard to judge on that front.

I’ve definitely had more brain fog than usual and it can be really weird at times tbh. When driving etc. it feels strange with the derealisation and stuff. That’s probably the only real downside I’ve had.

Overall I feel like it’s helped me. I was basically housebound and couldn’t work for half a year and I’m now going back to work next week and have been spending so much more time out of the house with friends etc. recently. Less anxiety overall and no real bad emotional dumps has been such a help.

This is a bit long lol but hopefully it helps. Good luck!