strike whilst the iron is hot
To make most of an opportunity or favourable conditions while one has the chance to do so. (A less common variant of "strike while the iron is hot.") Primarily heard in UK. This sounds like a pretty amazing deal they're offering. If I were you, I'd strike whilst the iron is hot. I deliberated too long before accepting the job offer, and now they've given it to someone else. I should have struck whilst the iron was hot.