There’s no such thing as a 33rd Degree Freemason. Therefore your question is asking something that is impossible to attain. So the answer to your question is: Never; there’s no such thing.
There are only three degrees in Freemasonry: Entered Apprentice, Fellowcraft, and Master Mason.
The Scottish Rite – and appendant body to Freemasonry – has additional degrees, including a 33rd Degree. None of these degrees are greater than or equal to the third degree in Freemasonry, that of Master Mason.
You can become a 32nd Degree Scottish Rite Mason in a weekend. It’s not that difficult. There are certain “required” degrees within the Rite and – once you’ve completed those – you can participate in the 32nd Degree. Taking all the degrees can be somewhat time consuming, as not all Valleys perform the degrees, and you may have to travel to other jurisdictions to get them.
The question, more properly, should be “how long does it take before a Master Mason is eligible to be elected to receive the 33rd degree in the Scottish Rite?”
The answer to that question is: 46 months (just under 4 years); the same amount of time it takes before you’re eligible to receive the red hat, denoting that you’re a Knight Commander of the Court of Honour (K.C.C.H.). White hats (33rd degree Scottish Rite Masons) are usually Personal Representatives for valleys. They can do other things within the Scottish Rite, but … well, it’s just a hat.