A
if it's an A-Flat scale the first note is A-Flat...
B
G
D
E
G
F
On trumpet, concert G is written A.
The first note of the major scale is the tonic.
It is the first note in the scale
The first note of a major or minor scale is called the tonic note. For example: for C major, the first note (or tonic note) is C; for a minor, the first note (or tonic note) is a.
The first note of a scale can go by many names. In solfeggio, it is "do;" in music theory it is usually the tonic or the root, but sometimes just "first." And of course every particular scale has its own particular note name for the first note.