Please help advice needed

Hi so I am 3 days late... I could definitely be pregnant which would be fantastic (my husband and I had sex on my ovulation days). My period cramps are normally pretty painful and I haven’t had any pain the past three days just been tired. Well my sister and I are normally close together with our cycles she is as of recent months a few days ahead maybe about 4 to 5 ahead. Today she called me on her lunch break and I was stretching and yawning and asked me what was wrong. I said nothing just tired. She asked, “the time of month?” So I just said yeah. She is nosy so she asked if I was on it or coming. Well since I’m supposed to be on my third day I said on it. I feel bad for fibbing but I had to. Because I’m not sure I am pregnant yet. It there is a possibility and I think you should normally wait a while to say something? There has been jealousy issues with her because I am a year younger and married and she is now back with her ex fiancé and felt she should have been married first and kids etc. I actually had to have a talk with her because a few months ago she kept bringing up if I was pregnant in a negative way and even said wait for her to get pregnant. After the talk she got defensive and denied being that way and said she wouldn’t bring it up anymore. I just hope she won’t rush it with her ex fiancé now bf again and have a baby just because I may be. I felt weird fibbing to her. Not sure how she will take it if I am pregnant but my question is how long is standard and a good amount of time to wait to tell your family? And how did you tell them? With a sweet gift like the ultrasound? This would be first time for my husband and I and my parents first grandbaby. Thank you