I am installing slate tiles on my staircase. I made a "bull-nose" for
each tread out of Ipe' hardwood by joining two pieces together with a
45degree lock miter joint. I then used some 1" wide strips of Ipe'
along both sides of the treads and risers to form a frame. So far so
good!

It is now time to lay the slate tile. Should I put the riser tiles on
first and extend them all the way down to the wood subfloor tread
tread. Or should I put the tread tiles on first all the way back to
the wood subfloor riser and then put the riser tiles on top of the
tread tiles?

If I put the riser tile on first my grout line will be on the tread and
vice versa if I put the tread on first the grout line will be on the
riser. It seems like it would be easier to put the riser on first and
let it rest on the wood subfloor tread while it dries and then I would
have more easier horizontal grout lines than more dificults to grout
verticle grout lines.

Anyone been here???

Thank you!