My (soon to be) pond will have an area that's about 6 feet wide by about 12
feet long, designed for water lillies - on the skimmer end of the pond.

How many plants would I put in?

I have a shelf built in, that's about 12 inches wide and 24 inches long.
How many water lillies could I plant in that space?

If I build a "pocket" for the water lillies to sit in, do I need to put them
in baskets (or some other container), or can I just plant them in the
pocket?

How long after I fill the pond should I wait before planting?

I'd ask for "artistic input" on a planting plan for the whole pond, but I'm
not sure how to get a diagram of it available for everyone to see.

Thanks!