I've been playing with Cheeky's spreadsheet, which I like since it has a shot rotation page allowing you to select your own rotation.
There does appear to be a bug on that page though -- if you select arcane, then it will shoot auto immediately, rather than with a 0.5 second delay. I did a combatlog to check what actually happens in the game, and indeed, the autoshot occurs ~0.484 seconds later.
The bug is in the P column equation. Currently, it is:
"Steady",BB4, IF(L4="Multi", 0.5, IF(L4="Aimed", BO4, IF(L4="Auto", 0.5,0))))
It needs to be
"Steady",BB4, IF(OR(L4="Multi", L4="Arcane"), 0.5, IF(L4="Aimed", BO4, IF(L4="Auto", 0.5,0))))
To fix the spreadsheet, enter the modified formula in the P4 cell, select the P4 cell, move the mouse to the lower right corner of the selection rectangle until the cursor changes to a +, and then drag the cursor all the way down the column stopping at row 53.