Examine the fascia to determine whether there are nail holes pre-punched in it. If there aren't, consider pre-drilling or nailing holes to minimize rippling and damage. Create a hole on both ends and one or two in the middle. They should be evenly spaced.
Measure from the top of the trim to the lower side of the soffit. Take 1/8 inch off of this amount and cut the fascia to this measurement.
Tack the fascia into place with small trim nails. Position a nail on each side of the panel and then one or two in the middle, evenly spaced. Use as few nails as possible to prevent rippling. Hammer carefully so that you don't dent the fascia.
Ensure that you do not hammer the nails too tightly. There needs to be a little bit of space between the nail and the fascia. As the temperature changes throughout the year, the material will expand and contract, and it needs the room to do this to prevent rippling.
Bend the fascia to a 90-degree angle to wrap it around the corner. This can be done by hand since aluminum fascia is flexible. Use a nail on each side of the angle to hold it in place.