First click in Minesweeper
I ran the custom version and designated a 9x9 board with 64 bombs in it. I then proceeded to click the smiley, then the square directly below the smiley repeating these two over and over again for 30 iterations. It never had a bomb in it. This is not reasonable if the probability of a bomb in that square were 64/81. I expect the actual probablility is zero that the first square has a bomb in it.
Then I performed 30 iterations of the following program:
1. Click the smiley
2. Click the top left square.
3. If it's a bomb, note what is in the square below the smiley, and go to step 1
4. If it's not a bomb, click the square below the one just clicked and go to step 3.
The square below the smiley had a bomb 27 times. This is probably reasonable given the probablility of 64/81 that the square would have a bomb.
Given this data, I expect that the calculation of the location of the bombs is delayed until the first square is clicked, not when the smiley is clicked.