Brio Zento

For those of you that have one of these, how upright do you have the seat? I mean while it is rearward facing.
I have mine laying back so it forms the tick shape that most convertable and capsules form but now the my son is a little older I was thinking I would sit it further upright and get some more space in the front seat as a result. I know it can sit upright rearward facing but just not sure on how old he should be.