Delay
Delay holds the growth wired into it back for a set number of generations, so parts of the tree start growing later than others.
Delay holds back the growth wired into it for a number of generations, so that part of the tree starts later than the rest. For example, a Delay between a trunk Grow and its branch Grow makes the branches wait while the trunk carries on extending.
It takes a growth graph on its Graph input and passes it on from its Graph output, so it goes anywhere a Grow's output would: into a Simulate, or into an input of a Grow, Split or Switch. The Delay tool on the Natsura toolbar (under Advanced) places one at the cursor.
The delay count generation setting is the number of generations to wait. At 0, the default, the Delay does nothing.
Split has its own Delay Growth setting for staggering its inputs, so you don't need a Delay there.