I told my mum straight away (I was 5w along when I tested) as she knew all about my trials and tribulations with TTC (I'd done IVF etc).

I held off telling my siblings until I had my first u/s - which I got done at 6w0d (note: this is not the norm, most women have their first u/s much later, but with my history I wanted the reassurance) and I saw the heartbeat, which means my pg was then classified as clinical (rather than chemical i.e. just HPTs and BTs).

It is really what you feel comfortable with, it is VERY exciting and telling them on your birthday sounds like a wonderful time!