The first time we booked a Van we wanted to ydrive at 9 o'clock, but we were there by 8:15, so we could take the sooner Van at 8:30.
Then we booked a Van at 8 o'clock and axtually drove at 8:30 - even though we were there by 7:30. It was fine, because the driver brought us directly to the Don Mueang International Airport where we originally wanted to go. ++
The busticket would have been way cheaper if we had bought it at the bus station. Over all, I would book the bus again.
On time, but not easy to find the bus station of Ayutthaya because on the map it indicate the school bus station, or the bus station for those travels is around 700 m far away on the street.
The bus is very noisy, too much air conditional.