Building Code gives me ~3/8" allowable variance between steps,
contractor gave me ~1/16" standard with a challenging wink, I kept it damned near ~1/8".
Do it before the HVAC duct butchers come in and do it.
That top tread.
I swear by that DeWalt saw for nice accurate cutting.
In the day I would wear one out literally every year.
Then the bottom fell out in 2008 now given light duty this one is still around since Dec 2007.
(It's nylon/plastic gears which makes it relatively light -
just don't hold up when being used hours on end, and in the heat.)
But, no other saw felt as good and accurate so it was worth it.
I also have a monster Milwaukee Worm Drive for the serious production cutting,
fortunately not much call for it these days.
Yup, talk about watching oneself age,
that Milwaukee beast was out front heralding my diminishing physical strength a decade ago.
I added blocking at middle and again filled in under stringers with some cutouts,
also tossed in an upright at middle of center stringer for extra bearing, for the heck of it.