Weekly GLP-1 injections are taken how?
Weekly GLP-1 injections are taken once a week, on the same day each week. MedlinePlus (NIH) gives the instruction for semaglutide in one line: "Use semaglutide injection on the same day each week at any time of day."
The NHS describes the same weekly rhythm for tirzepatide: "Tirzepatide comes as an injection that you use once a week."
Pick a day, not a time
The semaglutide instruction fixes the day and leaves the hour open. What matters in that wording is that the day repeats, so choose one you can keep from week to week.
Routine questions and questions for the prescriber
Taking the injection once a week is the routine part. Doses, a missed injection and side effects each need an answer for your own prescription, so those questions go to the person prescribing it.
If you want background on obesity itself, read MedlinePlus on obesity or Cleveland Clinic's overview of weight control and obesity. When tirzepatide is the medicine in question, MedlinePlus Drug Information on tirzepatide injection is the next page to read.
Before the first injection, ask the prescriber which day of the week yours falls on and what to do if that day slips.