Majimeche is a simple system to use.
Yet it also needs a full understanding of the results achievable. You mention that you have dark brown hair which can be anything from a base shade 2 - 4 depending on what tone your hair actually is. ...More >
I know it may be frustrating not been able to get into see your stylist but I would recommend that this would be by far the safest option for you as the colour achieved is totally dependant on what base shade you have to work off.
The majimech colour states that it lifts within fifteen minutes yet this is fifteen minutes from being in contact with the hair to be coloured. If you start at the back of the head and work your way up by the time the top is completed the underneath sections could have been on your hair for 30-40 minutes depending on the time in applying the colour, which would result in a lighter tone on the underneath compared to the last sections completed on the top sections of your hair.
Due to the above I would highly recommend you visit your hairdresser to ensure you get exactly what you want.