Something for developing the plan is customary. It should include a site visit and consultation too.

Absolutely normal!! I won't take on a design job without taking a deposit of a quarter to a third of my estimated fees upfront before any pencil hits paper. It reflects an investment of the client into the process and encourages a sense of ownership that will hopefully lead to productive interaction. And it covers time and effort the designer expends that sometimes, for whatever reasons, never materialize into a final product. It happens. And it's reassuring to know those 10-20 hours or more expended are covered and not just a write-off if the relationship goes south.

btw, online design services typically charge the entire fee upfront.

Definitely. We charge 30%.

I have paid for a plan (total cost up front) and then the estimate of labor/materials comes with the plan - so I have the choice to stay with the firm or take the plan elsewhere if I wanted