For me, I do 1-2 mins each time, no fixed amount, as long as she’s awake and free, I’ll put her in TT position. It can be from 1-6 times per day. When he cries, lift him up. Don’t let him associate TT to something detestful, just try again later. If my LO face down, I will just adjust her entire position (arms slightly crossed) then try again. If you adjust his head to face side ways, he’s just gonna lie down there.
We only started to do TT “religiously” when baby is around 3 months old and looking stronger haha. She’s fine, rolling at 4 month. Before that, it’s just like a fun play, for less than 1 min each time. We helped to cushion her chin with our palm whenever she faced downwards.