The first five minutes are everything.
When you scour Netflix for something new to watch, you change if something sucks for the first five minutes.
Books are cast aside if they don't draw you in within the first five minutes.
Music performances are met with a yawn (and sometimes an exit) if the first five minutes are boring.
With any creative work, put most of your effort into the first five minutes.
Otherwise, it won't matter what happens after that because no one will ever see it.