Wish takes less than six seconds to cast, but time isn't an issue
The casting time for Wish is 1 action. A combat round lasts approximately six seconds - so it cannot take longer than that to cast Wish - and it likely takes considerably less time.
However, the details of your wish are part of the meta game - not the in game casting process
The text says that when you cast Wish, you should:
State your wish to the GM as precisely as possible. The GM has great latitude in ruling what occurs in such an instance; the greater the wish, the greater the likelihood that something goes wrong.
Your GM is not an in game character - they are the person sitting with you at the table. Providing them with details is therefore not an in game action, and not part of the in game casting of the spell.
Spells verbal components are described as:
'...mystic words. The words themselves aren’t the source of the spell’s power; rather, the particular combination of sounds, with specific pitch and resonance, sets the threads of magic in motion.' (SRD p.101)
The mystic words your PC speaks in game when they cast Wish are not your precise details. Your precise details are part of your meta game with your DM.
There are no time limits on how you choose to manage your own meta game experience, beyond houserules agreed at your table.