Training battery

Unlike the much older Nickel Cadmium batteries, "training" or "conditioning" is not a thing with Lithium Ion batteries. Charge it when you want. Use the phone with whatever charge it came with. When it runs low or when you're ready for bed, put it on to charge.

See also:

When to charge your iPhone or iPad - Apple Community

The best method is to let it charge overnight. Don't let it drain to less than 10%.

There really isn't any training involved as the lithium ion battery inside your phone isn't susceptible to memory issues like the old nickel cadmium and nickel metal hydride batteries of the past.