One should be sure that he/she is going to Heaven once accepting Jesus Christ as one's personal saviour, for those who believe otherwise, am sorry I don't know. Once you have this ticket, the task at hand is to make righteous a part of your daily tasks, so that every day you are more white than yesterday. Of course there is a provision of asking for forgiveness one sin comes in, but one needs to enjoy everday life in salvation, live longer, healthy, wealthy, lovingly, as well as ready for the Kingdom, but not predicting if it's coming tonight, or the next evening. There, you will have time and resources in your haert to spread the Gospel. 

Jesus said that the Son of Man will come down without mercy because by then, He will be appearing as the judge between those who chose to take the narrow path, and the wide path.

He also promised that He won't have the time to listen to people pleading for more time to accept the Gospel of the goodnews of the Kingdom of God. That He will be comung down strictly to separate the dead from those to get everlasting life.