Not surprisingly, the one he uses the most (I think) is probably the most invisible. He uses it more often than you might expect him to use an adverb. You might say it’s barely an adverb, but still.

Any guesses?

Sufficient time has passed.  Give us your findings.

Now.

doh

In that famous Martin Amis essay about Elmore Leonard he describes a new tense that Elmore has invented, and certainly his use of “now” to move the action into the present is a big part of it.