Begin with 1 mg tirz for the first shot. If that feels fine after a day, do another 1 mg, then after another day add 0.5 mg. That gets you to 2.5 mg weekly for maintenance, and you can increase gradually later if food noise returns.
Looking for some input on switching. I've been using 1.75 mg of reta every fourth day for three months now, with my weight stable for the past month. Planning to switch to tirz for maintenance only. Hoping it will bring down my resting heart rate, improve HRV, and ease anhedonia. Any ideas on how to make the change, or thoughts that tirz might not impact those issues?