Run Up to the Big Day!
Buy some residue-free shampoo and starting using it. Regular shampoo is bad for dreadlocks and should be avoided! It is full of residue that clings to the hair and is extremely hard to wash out. Using reside-free shampoo for a while before the appointment can make the dreadlocking process much easier and can leave your head feeling more comfortable during the weeks after installation. I personally use a shampoo called Faith in Nature but there are other residue free brands too.
Try not to wash your hair too frequently. Hair will only get greasy if the scalp produces extra oil and this happens when the natural oils are stripped away during washing. Washing every 2-3 weeks is fine. Also, the more you wash your dreads, the messier and looser they will become. Washing your hair less frequently before the appointment will prepare your scalp for the dreads by producing less oil.
Stop using conditioner. Conditioner adds residue too and extra oils that can make the dreadlocking process more difficult, undo dreads and leave lots of nasty slime in them!
The Day Before the Big Day!
Wash your hair with residue-free shampoo (no conditioner!) rinse thoroughly and make sure your hair is completely dry. Do not apply ANY products including gels, paste, hair-spray etc.
Prepare yourself mentally for a head of fantastic new dreads!
During the Big Day!
The day will be a long one, so please remember to bring your lunch with you, and some snacks (depending on your appetite!). We can chat, listen to music or you can bring something to read. The day will be long so be prepared. I can supply drinks and vegetarian / vegan nibbles too.
I have access to most music (Amazon Music Unlimited) as well as suitably relaxing music. The length of time will vary but I will have given you an idea after talking with you about your requirements.