Willer buses - when to book?

I'm going to Japan in April and I want to use Willer buses this time (with a 3-day or 4-day bus pass).

I'm curious is it possible to book a bus at the last moment - for example day before the bus trip?

We want to give ourselves a bit of a margin and to decide how long we want to spend in Kyoto/Osaka and Tokyo on a daily basis... But I'm afraid that it can be hard to book a bus for a next day. Anyone have experience with that?

thanks,
K

The day before departure should be no problem (assuming, of course, that the bus is not booked out). It might even be possible on the day of travel, although now at 18:30, I am not able anymore to make reservations for this evening.

thanks! that's what I needed :)

I checked again today. The deadline depends on the route, but for the Tokyo-Osaka overnight route, for example, it seems to be possible to make reservations until 17:00 of the travel date, i.e. until just a few hours before departure time.

thank you! I'm touched by your hospitality. thanks again.

K