Yesterday I found small light brown patches in my undies and I haven't had my period yet.. but it was only a bit and I have had none since! Is this my first period if not when will it be?? I'm 13

That could very well be your first period.
Brown just means the blood and tissue were exposed to air.

That could very well be your first period.
Brown just means the blood and tissue were exposed to air.
Are you sure? It really wasn't much!

Most of us have a wide variation in our periods, month to month and year to year (I had very heavy ones until I was in my late 20s, I think, then they gradually got lighter and lighter until menopause).
We can never say we are 'sure' about anything online to someone asking about her body, but I'm pretty sure. But you are the right age to start, and I assume you have no horrible illnesses or STDs, and it's common to have your first period be just a little bit. So... start putting a little notation on your calendar and keep track. Notice how you feel, and avoid heavy foods and salt the week before to prevent bloating, try not to get constipated, keep active. If you feel crampy, do pelvic tilts. You may not feel any discomfort at all. I didn't get PMS until well out of my teens.

Most of us have a wide variation in our periods, month to month and year to year (I had very heavy ones til I was in my late 20s, I think, then they gradually got lighter and lighter til menopause).
We can never say we are 'sure' about anything online to someone asking about her body, but I'm pretty sure. But you are the right age to start, and I assume you have no horrible illnesses or STDs, and it's common to have your first period be just a little bit. So... start putting a little notation on your calendar and keep track. Notice how you feel, and avoid heavy foods and salt the week before to prevent bloating, try not to get constipated, keep active. If you feel crampy, do pelvic tilts. You may not feel any discomfort at all. I didn't get PMS til well out of my teens.
Thank you, that helped a lot! I don't have any illnesses so it probably is just the start of my period. I told my mum and she said its called 'spotting' or something?? :)