Here is the thing - if you wanted it OCD perfect then the tub should have been level. I for one would not cut the tile with that small of a difference. Alaska Man has the right method with furring strips but I am going to answer your question how I would do it.
Within reason - 1/8" for sure - I would widen the gap of the first couple at the bottom to meet with a level row one. That is my answer.
1/16" is very small spacers for that big of tile. You better take your time and triple check your alignments and please start with your most plumb corner. However there is nothing wrong with 1/16" gaps - it is just they are very unforgiving. Also just because your tiles are at 1/16" doesn't mean your gap to your tub has to be that.
And honestly if you had a true 1/16" gap to your tub that is really too small. Caulk will sit solely outside your tile and it will need repair more often. Even 1/8" can be too small of a gap.
The other part of this is that you would not be cutting an inch off. Shaving 1/16" from that big of a tile... that's tough to it straight with no nicks with the best tools.