I am tiling a shower/tub surround. I have applied roofing felt then cement
board to the studs (hardibacker). I then used tape and thinset on the
joints and corners - everything looks good and now I'm starting to tile up
the walls.

Is there a right or wrong method with regard to where I apply the thinset -
meaning on the wall or on the back of the tile? on the first few rows I
applied it to the wall directly but now am finding it easier to apply
directly to the back of the tile and then put it on the wall.

Is applying the thinset to the tile back OK to do?