taking advantage of a specific time or condition to perform an action

to seize an opportunity

To do something as early as possible, at the first opportunity, or before it's too late.

without extra effort or trouble while performing another task

to take advantage of a favorable situation or momentum to take further action

to strike while the iron is hot; to act while the situation is favorable

to take advantage of someone's misfortune or a crisis for personal gain

to take advantage of a weakness or a vulnerable situation to penetrate or enter.

to do something conveniently while in the process of doing something else; in passing

strike the iron while it's hot (idiom)

while it's still hot

to take advantage of someone's precarious situation or difficulties