Don’t forget to be as detailed as possible. The more detailed you are the less chance there will be of the trades involved having questions, which = either delays, guesses or assumptions.
It’s much better to put the time into writing accurate scopes of works and sketching detailed plans (including things like towel rail/toilet roll holder heights/locations) than picking up on things after completion. One person may have different “common sense” location/height etc, compared to the next persons “common sense”.

You can minimise any delays by making sure you’re available for phone calls at all times, just incase any questions arise whilst the work is being performed.