It serves a couple of people very well. The current timeline for tabling the budget gives a lot of flexibility to the government and to the Minister of Finance to table a budget when they are ready and when it suits them, whereas a fixed tabling date for a budget or a shorter window, an earlier window, would force the government to table its budget at a time that may not be convenient or at a time when there are still lots of unknowns when it comes to the specific decisions that the government has not yet made.
On May 8th, 2023. See this statement in context.