No type mentioned, so I can approach this from 757 perspective. Gear down, Flaps 20 at the same time is normal. Asking for F25 while the LG is still moving is asking for a landing config warning. So that’s an ASR and paperwork that could be avoided by waiting another couple of seconds.
Edited to add. Our part B does indeed put a responsibility on PM to check gear is down before selecting landing flap but why put them in that position?