Can you float runes (exhaust runes to add energy) after playing Bullet Time but before it resolves?

Ruling: Yes, you can exhaust runes to add energy after playing Bullet Time but before it resolves. Runes may be used any time a card asks costs to be paid, and all Reaction speed ADD abilities can be used before or during resolution.

Sequence:

• Play Bullet Time (it goes on the chain)
• Before passing priority, you can exhaust runes to float energy
• If both players pass priority without floating, it becomes too late to float energy
• Bullet Time resolves

Nuances:

• If you don't float energy before passing priority after playing Bullet Time, and your opponent also passes priority without playing something, it's too late to float energy at that point