How will I no when my pug puppy comes into her first heat?

she will swell up on her back end and she will have drops of blood coming from that area scoot acoss the floor trying to clean it up but can't due to being in heat and first time she will come into heat about 6 months or a little later yea it will happen soom some come before their 9 months or so you have to keep her away from other male dogs unless you want puppys