You start therapy and wait. The beginner question is when you will notice anything, and the honest answer is a range, not a date.
The timeline the source gives
my.clevelandclinic.org states: It may take a few weeks before you start noticing differences in your body and mood once starting TRT, and that is a rough guide with no promise attached. Anyone quoting you a specific day should be asked where the number comes from.
Reading both sides
Healthline covers hormone replacement therapy for men, and a second piece covers HRT for males, its benefits, risks and more. A narrative review of testosterone replacement therapy in men aged 50 and above is more clinical. The article titled Testosterone Therapy for the Treatment of Age-Related Hypogonadism: Risks with Uncertain Benefits states its caution in the title: the benefits are uncertain.
The cheap step and the step to leave alone
The cheap step is to keep a short note each week on how you feel. Changing a dose or stopping is not a do-it-yourself decision, so raise it with your clinician.
Take the note to your clinician
A licensed clinician can read your notes against your plan. Bring them to each visit and ask what to expect next.