Yorkie,.. the only thing I`d caution you about is using wax-type products on the hair is that [ I`m thinking of one in particular..a well-known brand ] they can be very difficult to remove and need powerful shampoos and even a product-specific shampoo to get fully out of the hair...this is obviously not great for system hair as it`s ` harsh` and will lift your colour noticeably in a short space of time. Silverstreak`s routine is ideal really ...... I even find things like Brylcreem [Pomades] can build-up quickly and leave the hair looking greasy / lifeless.
A good daily spritz with water and the addition of a good leave-in conditioner [I use PPI `Enhance`,daily leave-in conditioner --also has UV Protection in it--- available in UK from bargainlacewigs.co.uk] is ideal......the Back2natural will really help mask any variations in shade at this early stage.
It`s worth pointing out too, that whilst your stylist was referring to colouring it..... male and female hair is different in chemical make-up........ I was chatting with a guy who is a colourist in a `normal` hair salon recently....... he was explaining it to me........ even the factories have 2 different colour-rings [charts] for men`s and womens` hair..... most system hair is of female origin / was growing on female heads originally, so it may very well ` take` colours differently to what you might want or expect...... colouring can be tricky with browns and blondes...there are so many shades...... you should be ok though as your hair is quite dark..... I usually go for colour ` 1b` [off-black / slightly brown] ---it becomes relatively ` starker` brown as it oxidises over time..... I use a Black colour and only apply it for max. 3 minutes when I want to darken the hair down again....... even though I`m using ` Black`, by just leaving it on for a very short time, it doesn`t end up jet-black, but more of a deep Brown --kind of borderline black ! System hair also ` grabs` colour and goes very very ` deep` in terms of shade, literally in minutes ,compared to growing hair...... it can be a bit of a minefield with other tones, but in time, should you need to deepen your particular system, I`d say you should have no real problems getting it right...for now though, juut apply the Back2natural and I think you`ll be really happy with it !