I would imagine a small period of time would be needed to check for reactions (which are not uncommon) but the situation is more likely to generate an investigation as to why you need the statins in the first place. Chances are you will be asked to complete a Cardiac revue with both static and exercise ECG's.
See here:
CAA Cardiovascular Requirements
Regardless of the above. Do your own research as to whether you wish to commence taking statins. There is a lot of controversy surrounding their effectiveness and the side effects they generate. I personally chose to keep well clear of them, especially when my vet told me to avoid them like the plague.