help for stepper motor delay time

i am using a STH-39D Shenino stepper motor, 1.8 degrees step angle. what is the delay time i should give to energise two adjacent colis. i have given a 1ms delay time and it failed ti rotate.

so wats the exact delay value for my motor

It depends how long you want between steps, to reduce the time (and make it faster) you need to power it from a MUCH higher voltage, with current limiting.

Start off with a longer delay time, then reduce it and see where it loses power.