How long does the buyer have to deposit earnest money? (Texas)

[Bryce Y.]

Hey guys,

A couple days ago I got a house under contract.  I am the seller.  The buyer said they will deposit the earnest money the next day.  It has been 2 days and the buyer is not responding.  The contract reads, "If Buyer fails to deposit the earnest money as required by this contract, Buyer will be in default." 

It doesn't address a reasonable timeframe. The option period is 7 days, and closing is in 30 days.  At what point am I free to make a contract with another buyer?  

Thanks.