To tell or not to tell

So I recently just had a job interview that seemed to have gone very well and I’m pretty confident I got the job as they said I should hear from them by the beginning of next week. While I am excited I’m just nervous because I am 18 almost 19 weeks pregnant. Im still able to cover it very well so I didn’t bring it up in the interview (I’ve read that that is not something you are required todo) but because i am somewhat far along and I know soon I wont be able to hide it i want to know how I should go about telling them. Should I just wait until they ask or be upfront once they set me up to actually start. My only concern is explaining ill have to miss time for my appointments. Luckily my home hospital and job are all on the same road so I wouldn’t be missing hours for appointments maybe 45 min top that shouldn’t be a problem but I dont want them to think I wont be reliable and once the baby comes because I would like to be able to go back to work after my maternity leave is up so I can get right back into things. Im asking in this group since we all just had our babies recently so I know a few moms have had to experience this already.