Each stylist may have a preference on how they would like you to prepare you hair. My preferred method is to;
Book a trial at least two months in advance to get the time you want. Consider having it one to two months prior to the wedding as hair is close to the length it will be.
Have your hair coloured the week before so it settles and you can get a better picture of hair style. too much regrowth or tone not right will distract from style.
Do weekly treatments leading up to your trial and wedding day. This will close the cutilce (outside layer of the hair) and make your hair shiney and easier to manage.
Wash your hair the day prior to the trial so it can settle with some natural oil but not be too dirty. i will then prepare the using specific products so do limit fuzziness.
Bring pictures or start a Pinterest board of ideas and be prepared to alter style depending on hair density, length or weather. Have a few variations you are willing to look at. If you are not sure I am always happy to help with ideas with purely an idea of what your dress will be and create a style to suit you.
A trial is normally one style with variations (plenty of variations if needed) made to it. If you would like to try more than one style it may cost more but that is always specified.
Look at the style in a photo as sometimes it is hard to look at ourselves in the mirror and make a decision where we can connect better seeing ourselves and hair in a photo.
Don't forget to take any hair pieces or veils to your trial as it can help determine the final result of the trial. It isn't necessary but it helps.