If there was a closing deadline and it passed, they may say you didn't close by the deadline in the contract so the contract is null. 

But if you give them a deadline and a bonus the outcome is different.   

I’ve offered him his deposit in cash when he hands keys to me on or before deadline, but that doesn’t seem incentive enough.

@Etan Frankel although the government has a hard deadline of April 20th, 2018 to establish designated opportunity zones nation-wide, the investments wont happen for a short period afterwards while the IRS works on designating qualifications for the certification of an Opportunity Zone Fund.As soon as the certifications have been designated and the flood gates for applications are opened, i am sure you will begin to see many Opportunity Fund's pop up that would be eager to participate in the investment.

They have nuclear weapons they win the argument.The 45 day deadline is for real. 

And if you did, what happened may be retaliation.On them legally notifying you, if you received it on the 31st day, by certified mail, they may have barely met the deadline, or maybe not.

The only thing schools force you to meet deadlines and a bit of discipline to get things done. 

Broker has left a message asking if I am still interested - while ignoring my first offer - with the end of business today being a deadline for offers.

I think the most important part is that you set a hard deadline and stick to it......

Work the system and deadlines as tight as you can and if you don’t know what those deadlines are get a rent court attorney or agent familiar with your county and pay them to do it or you will get screwed even more by time.