How can I convert Grease Pencil's 'Build' modifier to keyframes? I am completely new to blender and started to learn it for 2D animation purposes.

I experimented with the grease pencil modifier "Build" but I can't figure out how to convert the animated sequence into keyframes. 

I would like to have every stroke converted to keyframes in order to adjust the timing of it, remove/add lines etc. Any ideas?
You can divide the various strokes into layers, then add more than a build modifier, targeting each one to a single layer. Then every build modifier can be set to start at one certain frame and last for any number of frames.