Daytime calls get answered most reliably; otherwise leave a voicemail with your town and roughly how many windows, and a local cleaner rings back — typically within a business day, longer during the spring and fall rushes.
Ask for a route quote (per-visit price on a schedule) rather than a one-off — it's almost always the better math for commercial glass. Say the street and the frontage size and you're most of the way to a number.