Call, email, or send the form. Whichever you use, you are reaching me rather than a service center.
If you already have your current declarations pages, send those and skip most of the back and forth. Everything an underwriter needs to start is already in that document, and it lets me tell you what you actually have before either of us talks about price.
If you do not have any of that handy, send the form anyway. I would rather start the conversation than wait for paperwork.
Same day during the week. If you are a buyer under contract with a closing date, call rather than email, because that is a situation where an hour matters and I would rather not have it sitting in an inbox.