How many weeks do you start wfh?

Hi mummies, when are you intending to request to wfh? I’m at 27 weeks and I’ve a low placenta. These days it feels so heavy to walk and some days it feels like baby is resting really low. I also have to carry my laptop to and fro work everyday and i feel so breathless just from the transport to and fro home and office 😭😭 But I do know some gynae are super strict with their HL/letters. Intending to speak to my gynae soon at my 3rd trimester check.