If i were you id wait till you buy a pram and check to see if you can get one with an integrated car seat that you can clip in to the pram / buggy then unclip and use it as a car seat ! These are the best thing in the world as it means you dont waken the baby when transfering baby from buggy to car and vice versa, trust me they are so much better when sleeping !
Then when it hits 9 months get pne of these