has begun or begins

[arzgol]

She has a part time job but her boss begins/ has begun to increase her workload.

Which tense should I use?


Thank you so much.

[5jj]

She has a part time job but her boss begins/is beginning/ has begun to increase her workload.

It's grammatically correct with either of those two versions, but it is not very clear. How does one increase a workload for a part-time worker in a way that is different from increasing it for a full-time worker? Without more context, 'but' seems an odd word to use here.