I have a bugaboo bee (not plus). My baby is nearly 13 weeks and i have been using it in the flattest position with the cocoon. He is tall and is getting a bit big for the cocoon. At what age can he go without the cocoon and more upright? I would be interested to know other peoples experience as i cannot find info in the manual. He is more alert now and although I pull the hood down, think he would enjoy this. I have a fleecy inlay for itl.