A time skip might be an option to consider. Although, I still do not see it as a figurative 'cure-all' for the pacing of the plot in and of itself.
You should also keep in mind that even with a time skip option inferred, NTR man still has to create those additional scenes, perhaps create an entirely new model wherein the mother will appear a bit older (and, if enough time has passed, would make mom possess some outwardly apparent "gyaru" characteristics as a result of being tainted/corrupted by the MC's bully (e.g., blonde hair, tanned skin, tattoos, etc).
Then you have those new scripts to accompany the time skip transition, and so on and so forth. So, in practice, even with a time skip option enabled I still see that as eating up additional development time in the back-end process.
P.S. On another note, even despite the time-skip option, the whole notion of a mother just leaving her child behind to hop on the bully's dick, no matter how sexually frustrated she may be with herself doesn't really seem all that realistic to me either way.
If she was a 'wife', sure makes sense, a 'sister', fair enough, or even a 'childhood friend'? All are scenarios that can be crafted and moulded to appear more realistic (and/or tolerable) to a certain extent.
But a mother? One that has given birth to her own flesh and blood, leaving behind her only child to bask in utter despair and hopelessness just for the sake of satiating her own sexual desire and/or lust?
That, (in and of itself) is as extreme of a direction that NTR can take, imo.