One primary source you might be interested in is the Strategikon by Maurice. It was probably written in the sixth century and is a military handbook filled with commands. There are so many commands in it that I’m not sure what to give as examples, but here are a few:

If the commander wants the troops to advance, he shouts out ‘March’ [Move], which would be kineson in Greek… If he wants it to stop, he shouts the command: ‘Halt’ [Sta]… In case he wants them to march in open order, the command is: ‘In line. March.’ [Equaliter ambula] To close ranks with the greatest precision by the flanks and the rear…the command is ‘By the flank. Close’ [Ad latus stringe]… At the command, ‘Close ranks’ [Junge], the soldiers close up from the rear for the charge. With the troops marching in close formation, particularly after they have closed in tightly from the flank, the archers open fire, and the command is given: ‘Charge.’ [Percute]

These seem to be fairly formal commands so I’m not sure if this is exactly what you are looking for, but there are some other quotes Maurice mentions in drills which might fit:

Do not fall back. [Nemo demittat]… Keep your eyes on the standard [Sic venias vero aequalis facies]… This is how a brave soldier should act. [Talis est comodum miles barbati]

Source: George T. Dennis, Maurice’s Strategikon: Handbook of Byzantine Military Strategy