Gotta get it while the getting's good
Gotta strike while the iron's hot, before you stop

from Jay Z – My 1st Song Lyrics on Rap Genius

Meaning

When a blacksmith puts iron in a forge and heats it up, it is most malleable right after it’s removed from the forge and it’s still red hot. The blacksmith has to form it before it cools down and re-hardens, or else he has missed his opportunity.

In other words, take advantage of the boom in order to make the most of it.

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