Stretching Wake Windows

Start stretching when he's ready for two naps and showing signs. You don't want to be keeping them awake much longer than 2/2.5 hours on a 3 nap schedule or they'll have too much awake time. 2 naps is the point you can transition to 2.5/3/3.5 or 3/3/3 hours of awake time.

I use this as a loose guide. It works for my bub.
I've found sleepiness is like hunger .. they don't extend it themselves. We go from feeding or sleeping at the first signs, to delaying and helping them go longer. I think of it as "solo play" when she's fresh, and "quiet play" or "cuddly play" when she is approaching a meal or nap.

They stretch their wake time themselves. Just watch her tired cues and with time naps automatically move later and later until it's time to drop one nap or bedtime will be past 10 pm.

My daughter has recently transitioned to 2 sleeps a day, she done it herself, and i just followed her sleep routine

I didn’t do anything to help mine, she just did it herself. I started noticing her first nap was getting a bit longer, which pushed everything back. I always want her bedtime to be around 8:30 so made sure she didn’t sleep past 6. So as her nap was happening later and later, I had to start cutting her off.
All of the shifting just happened naturally