Is it true that you get your stipend z points on your birth date of every month?

Not quite. If you're a gold account, you get it the day after your monthly payment goes through, or if you're on a lifetime subscription or multi-month payment, the day after the date your last payment went out.

yes sorry, I forgot to mention that I am a lifer

I usually get mine the day before the anniversary date of my subscription (bought my lifetime sub on April 17, 2011, get stipend on the 16th of every month). That's how the veteran rewards used to work- still work, I suppose- you get them the day before.