Baby outgrowing Bugaboo stroller bassinet

My baby is 3 months old and in the 98th percentile. He’s 18 lbs and quite long too! He is quickly outgrowing our Bugaboo Kangaroo bassinet (weight limit is 20 lbs). What should I do when he no longer fits? When to move him to the toddler seat? Does anyone with the Kangaroo know how far the seat reclines and if it would be okay for an infant? Should I try to buy the Uppababy Snug Seat to use? Help!