I’d focus on counting out loud before you try and play a more advanced roll pattern.
The timing and counting of the forward roll will be the same as the alternating thumb roll. It just doesn’t divide evenly into the measure like the alternating thumb roll does.
So if you do T, I, M, T, I, M, T, M (one common forward roll) the count will be 1 and 2 and 3 and 4 and.
What you can do is practice counting along with the metronome. Start by counting 1, 2, 3, 4 each count on a click. Then see if you can add the “ands” by counting 1, and 2, and, etc…. The ands will be counted between the clicks.
If you’re doing this correctly you should be able to switch back and forth counting just 1, 2, 3, 4 and 1, and 2, and, 3 and 4 and without anything changing on the metronome.
Once you can count it confidently out loud. It will be much easier to play.
Let me know if you still have any other questions. – Mike