My question to you is, Did the thief on the Cross go to Heaven? If the answer is NO, then Christ is a liar. If the answer is YES, when was he baptised?
The answer is YES, and he was NOT baptised, and if you were more familiar with Catholic teaching you would understand the axiom that while we are bound by the Sacraments, God is not. Therefore, God can choose to bring someone to heaven who is *not* baptized, but it will be an extraordinary manifestation of His divine prerogative and does not by any means take away the fact that Baptism by water and the Spirit remains the *ordinary* means of bringing one into the Church. St. Emerentiana is in heaven, and she was never baptized with water either. One can also be baptized by desire, and by blood--and that is well-established Catholic theology.
Yes.
If the answer is YES, when was he baptised?
Traditional baptism is normative. The thief's act of faith was a baptism of desire. Traditional baptism would have been difficult considering the circumstances.
And what about the fate of those who died before baptism was instituted as a sacrament? And what about the fate of those who are ignorant of the importance of baptism?
The Church teaches that unbaptized people who serve truth to the best of their ability may be saved. Their salvation would be through Christ, despite their ignorance of Him.