What I do here is 9am I pit them down for a morning nap and wake them up very latest 10:30am. They would normally wake up at 10am though. And we go out etc. Again for afternoon nap I put them down between 1-1:30pm and they sleep until 3- 3:30pm then diaper change, snack time etc. And they are ready to go home at 4:30-5pm.

I personally would not cut their sleep but play with the timing as they are very young and for their growth they need to sleep.

If you can take them out in the morning after their morning nap they will be tired again for their afternoon nap.

Hope it helps.