This is the first question I or any other stylist should ask when you request a service. Most generally we, as professionals, can tell approximately how long it has been, but we want confirmation of the unknown. This drastically changes what and how we get to the point you desire.
There are many things that affect how color takes, how it lasts, how it fades, etc. The #1 factor is what is in your hair to start with. Every single color, even temporary will affect the end result of anything I put on your hair. Hair grows approximately 1/2" month; so if your hair is 6 inches long, we have to take into consideration everything your hair has been exposed to in the last 12 months! I don't care if it is semi-permanent or "your natural hair color" it will make the end result different.
Let me tell you a story of someone who put their "natural" color in and came in the next day for a hair color....The client had Level 1 colored hair (That's black in hairdresser talk.) This person wanted their natural black with steel grey and Sapphire blue highlights. Very doable...on Natural Hair...
So the client who assures me it's "natural" color and sat in my chair. Now 2 days is not enough time to leave a line of demarcation so I could see the difference. I paint lightener in the hair thinking it would get to a light tan which would give me a good base to get the steel color and sapphire to take like the picture I was shown. I applied the product and processed it the recommended time...It was bright apricot! not on a natural spectrum at all! I ask the client again, what do you have in your hair? "Nothing. It's my natural color." I know that this head has been covered in another artificial color, it was not your original natural color. I reapplied the lightener a second time and the hair turned hot pink! I asked what profession they were in and it wasn't a profession that would raise a red flag that would cause a strange chemical reaction to happen.
I explained that there was obviously something in the hair prior to me starting the service, and I needed to purchase another series of color and a product remover to "fix" the "natural" color.
We take a lot of things into consideration when coloring hair, and each "natural" hair color has what is called an underlying pigment. The bright apricot and the hot pink were the "artificial" underlying pigments that were in the box color of what was in the hair to make it appear to be the client's "natural" color.
For those who know me, know I love to color my hair. My natural color is almost black, like a dark dark brown, so anytime I lighten my hair, I have to remember that my underlying pigment is a red-orange. It is because of this that my blonde tends to get "brassy."
So, please for my sake, your hair's sake and any other stylist out there who may do your color; be honest! In fact I have a few clients that I know like to play with there hair color, I recommend doing one of two things; #1 take a picture of the box and or #2 record the brand and color name you applied. Your hair will thank you, and so will I!