Other companies use a mobilisation plan, and then stick to it.
Write down everything that you need to do, then put a start date and a compleated date next to it. a Project plan, agree it with the customer then deliver against it
Include everything, from adverts to zone numbering for the cleaning specification and staff training.
I would start by identifying how the trial is being measured in 3 months, and what is classed as a pass and a fail. If this includeds TUPE.
I would also make sure they are paying a premium for the trial, as your costs will be higher
Good Luck
Geoff