Cosleeper + new addition?

For those of you who made that choice, how did you deal with a coslept toddler and a newborn? Our 18 month old is very comftorable sleeping with us and i'm also 29 weeks pregnant. The plan was to transition him beforehand, but due to our living conditions (all in one room) he sees his little bed beside our big bed as a joke. I'm just kind of curious as to what you guys did? And how cosleeping/not worked out for the second baby. Tips, tricks, shared experiences are appreciated!!