Once you have chilled a white wine can you store it at room temperature?

No it doesn't need to be refridgerated. If you are storing it for a long period it ia better to keep it in a cool, dry area, ideally a wine celler.

About 2 hours before serving put it in the fridge and serve chilled.

Interestingly, although white wine is served chilled for all WSET exams it is served at room temperature, the same as red wine!