HELP! I Need some advice! Pregnant and starting a new job

I will be 20wks on Friday. I had an interview for new job today and should hear be updated Friday if I move on to the next phase of interviews.

I haven't told them I'm pregnant and the clothes I was wear hid my pregnant belly... I'm over weight anyway so it's not very obvious yet I'm pregnant.

They asked if I could dedicate at least a year uninterrupted because of training and getting traction in the position. I said yes since I didn't want them to not consider me because I'm pregnant.

My question is if I am offered the job do I tell them then I'm pregnant or wait a few weeks to tell them?

I'm Canadian so I get at least a year off for maternity leave... ugh I don't know what to do and I feel a little guilty for lying that I have a year because I only have a few months 😬