Whenever a person is financially and physically able to perform Hajj, he should not delay it. As for supererogatory Hajj or `Umrah, he can change his mind and choose the time that suits him.
In this regard, the Saudi Muslim scholar Sheikh Ibrahim Al-Khudayri states: With regard to obligatory Hajj, one should hasten to do it, because the Prophet (peace and blessings be upon him) says: “Hasten to perform Hajj, for no one of you knows what will happen to him.” And `Umar Ibn Al-Khattaab (may Allah be pleased with him) said, “Whoever dies without having performed Hajj when he had the means to do so, he may as well choose to die either a Jew or Christian.”

As for supererogatory Hajj or `Umrah, a person can change his mind, and he does not sin by doing so, so long as he has not commenced the rites of Hajj, because Allah says: (And perform properly (i.e. all the ceremonies according to the ways of Prophet Muhammad), the Hajj and `Umrah (i.e. the pilgrimage to Makkah) for Allah.) (Al-Baqarah 2:196). He may choose the time that suits him. Even if he has resolved to travel and (for that purpose) then changes his mind, there is nothing wrong with that.