This is a Stair Rail we did at DenverStair.com
The newel for the stair rail fits over the top of the Sure-Tite bolt. After bolting in tightly. Check it for plumb on both sides. Cut the bottom to adjust and reinstall. This method of attachment takes a little more time. The results are superior to metal brackets with moulding to hide them. My objection to 4j anchors is two fold. The screws loosen over time. ( I have repaired many) The aesthetics are ugly to me. I like the plain simple connection of post to floor without adding a piece of moulding that looks like your hiding something.
Determine the handrail length by measuring at the bottom between the points. Check that the walls are plumb and again adjust if necessary. After cutting the stair rail to length we put in the rail bolt holes. Pics below
Using a 1 inch sharp paddle bit, drill the hole for the rail bolt captive nut. Forster bits work fine as well. You can use a forstner bit. I prefer the spade bits because they are easily sharpened. Then using a 3/8 bit drill the end hole for the rail lag bolt. Pic is below. From the bottom of the rail this is 7/8 to center. Try not to go much higher as it makes it tough to thread on the captive nut.
Measure in on each end of the rail for the starting balusters. I use 2 3/4 inch, again this is the starting and ending baluster in your rail. Measure between these points to determine your baluster spacing. 4 inch on a guardrail and 4 3/8 on a rake rail. Those are the inside spacing between balusters.
Install the rail bolt lags into the newel post. You will need to calculate the height from the floor to the center line of the rail lags.
Now you can install the rail between the posts. I keep the newel post bolts loose until this step. Tighten them down at this point. Then install the rail bolts into the railing. You will need a rail wrench like the one pictured above.
We then use a laser to mark the floor, indexing on the rail holes above to the location on the floor for the baluster holes.