You can drink a potion and postpone its effects.
Prerequisite: Knowledge (arcana) 1 rank.
Benefit: You can drink a potion and delay its effects for a number of hours equal to your Constitution modifier (minimum 1 hour). At any time during this period, you can activate the potion’s effect as a swift action. If the duration expires before you activate the potion, it is wasted.
You can delay only one potion at a time. You must activate a delayed potion before you can choose to delay another one.
Source: Complete Mage, page 41.