@MysteryTripAgain
Thank you, both your explanations are factually correct and enhance my point.
However, there is more context to the statements; to whom they are said and in response to what.
'I knew what what I voted for', has been said in response to a typical Remain argument, which is actualou long the lines of what you say above;
'You didn't what you were voting for, there was only Leave or Remain on the ballot paper, there was no information on how we would leave, so how could you know the consequences' (or benefits depending on your viewpoint).
The 2nd statement is often said in response to Remain voters when they point out possible pit falls, financial losses and other undesirable outcomes of Brexit.
There may also be responses such:
'We'll be fine'
'More project fear'
'Another Remainer crystal ball'
'No one actually knows, so how can you say that?'
As you so rightly pointed out, negotiations could not begin until 1st February 2020. Therefore all predictions of economic prosperity, a 'new dawn', great trade deals etc etc, are all also, at this point, unknowns.
So perhaps the more accurate statement to say, rather than 'I know what I voted for' is:
'I voted only to leave the EU. I don't know how or when that will happen or what the consequences or benefits will be. I only know I voted to Leave'
One can make educated forecasts, or speculate as to the possible outcomes, or projected economic growth, but I know that some leavers apparently don't trust experts so they wouldn't take that on board.
So actually the Brexit project is a gamble based on faith. Faith in BJ to negotiate wisely and deliver the promised Brexit of the Leave campaign. After all, no one knows.