The problem I have always faced installing stairs direct-glue is getting the carpet to conform to the nose. Usually these types of installations are with commercial grade carpet, Unitary, Hot-melt, or other heavy and quite often stiff backings.
Traditionally, contact adhesive was used to overcome the resistance of these carpets to being conformed to such tight turns as are present installing a staircase.
First, spread the stairs with adhesive; use plenty -- DON'T SKIMP! It is important to use a high-solids premium multi-purpose; you'll want something with lots of grab. Next, use a fan to help flash off, and accelerate the adhesive set up (Photo 1).
At this point the carpet will bubble at the nose. The solution is to steam the carpet, causing it to relax and form to the stair contour.
1. Use a regular clothes iron and a white dishtowel; if white isn't available, make sure the towel is colorfast, because on a light carpet you might have a color transfer. In this case, the gray stripes were not a concern because the carpet was the same color gray. Wet the towel and wring it out so it is just damp. Place the towel over the nose of the stair. Apply the iron to the towel. This will create a blast of steam, instantly softening the carpet allowing it to conform to the stair nose.
The tacked up adhesive will grab the softened carpet, and when it cools it will have assumed the shape of the stair firmly held in place by the multi-purpose adhesive (Photos 3 and 4).
2. A safer approach is to use a small portable steamer available from your local distributor that will not damage the face fiber of the carpet. The procedure is the same as using the iron, but the towel is not required because the bottom of this steamer doesn't heat up (Photos 5 and 6).