I have to agree with Mr C, there is no easy answer...
Even in full size racing there is the dilema of what to use when... Some series allocate a specific number of tyres per race weekend, so the question becomes what do we use for practise, qualifying and the race(s), new, scubbed (usually only 1 maybe 2 laps use) or used? Should we scrub the race tyres or save new ones for the race? When are the tyres at their best? 3 laps old, 10 laps old?
Of course the answers to all these are dependent on many things such as (in no particular order):
How hard is a driver on tyres?
How abrasive is the track?
What is are the tyre compounds/construction best suited to?
How long does it take to achieve optimum tread temperature?
How long does it take to achieve optimum tyre pressure?
How many tyres do we have?
What is the weather like?