If I’m on the fence about resigning, can a company legally ask me or give me a timeline on when I must let them know when I plan to resign?

Hello,

Nothing prevents your employer on when you plan on resigning but you are also not required to tell them if you haven't made up your mind. Your employment contract may include a certain amount of notice to provide to your employer and it is generally courteous to give at least two weeks notice. Depending on how important you are to your employer's operations, you may also be required to give more notice.

Regards,

Lluc Cerda
Lawyer