Is it ethically appropriate to work with more than one real estate ...

In general, we are able to schedule showings on a short notice, unless the property is occupied than usually 24 hours notice is required. 3 or more days-very unusual, unless the listing agent does not respond. I would talk to your current agent and ask what is a reason behind such a long time for scheduling showings. Than, you can decide if it is better to find another agent or continue working with current one.
Good luck!

Source: http://www.zillow.com/advice-thread/Is-it-ethically-appropriate-to-work-with-more-than-one-real-estate-agent-at-a-time/501689/

mark zuckerberg mark zuckerberg maurice jones drew Yash Chopra George McGovern braxton miller braxton miller