If a believer professes that Jesus is his/her lord and saviour and asks for forgiveness of their sins,they will go to heaven if they pass away before getting baptized.The reason I know this is because of the thief,crucified at the side of Jesus.He didn't have time to be baptized,but asked for forgiveness.Jesus told him that he would join him in paradise that very day.
We still are told to ask for forgiveness and be baptised,but if something were to happen before you had the chance,God would be quite understanding.On the other hand,if you know you need to be baptised,but either don't do it or put it off for some time,well,only "the Big Guy" can answer that one,but I'm inclined to believe that this wouldn't be a good scenario.
Quack: The thief on the cross died before Christ's mission was complete. The thief died under the old law of Moses, not the new law of Liberty under Chist Jesus. You are talking about two different dispensations. Christ's sacrifice was not yet complete. Christ had not yet died for our sins, and be buried, and then raise again on the 3rd day. Different dispensations, different modes of salvation.