No showings until due diligence

[Account Closed]

Looking for my first house hack and I found a 4-plex listed for $500,000. They only have pictures of the outside and, since all unites are currently occupied, they won't do showings until after my offer is accepted. That makes it difficult for me to know what to offer. I have no idea what the insides look like, so I don't know what kind of rehab budget to be prepared for. Should I offer a lower amount assuming there will be extensive rehab? Or should I offer higher, and then pending my own inspection of the property, request to come down in price? Also, how much time should I ask for due diligence? This is near Atlanta, where houses are selling crazy fast. My agent has told me I won't be able to get any offers accepted if I do more than 12 days on a single family home, and for this one thinks I should only go up to 20 days. What is the best way to go about this situation, since I don't really know what I'm buying?