You better start low because the side effects are unpredictable. You may feel nothing, or you may spend three days crawling to the bathroom every half hour.
Reta has a 6 days half life, and it takes 4-5 weeks for a certain weekly dose to stay stable in your system. This means you shouldn't go higher every week. See how you feel, what difference you notice. Find the minimal effective dose, and stick with that as long as it works for you. Only raise if you stop getting results. That's the basic plan. You can follow the official titration protocols, or do something milder. Some people are fine with titrating the way the studies did, others would die from the sides if they raised so much.
And seriously: Tiktok? This is something you inject in your body. Do some actual research, which means reading studies, not watching some moron running their mouth in a video. Videos are for people who can't read.