One question I get a lot is about what a contingency is in a contract. Basically, its a time period for you to do your investigations and get your loan fully approved before you are 100% committed to buying the home. Usually you get 17 days to review material facts about the house such as seller disclosures and get a professional inspection on the house. Then you have 21 days to make sure the loan is golden and you have final loan approval to close.
One thing to point out is that contingencies are active, not passive, meaning that even if the date arrives, you have to physically sign off on the contingency, it just does not automatically remove itself. So, if you need a little additional time to get things lined up, you can request the time from he seller. He may not grant it, but if the date comes and you have not removed it, they can serve you a perform or quit notice and you will have a short period to get things in order.
It is never a good idea to enter into a contract with the intention of "I can cancel whenever I want" so you really do need a good reason why you are canceling if its been a few weeks into the escrow. Remember, even though you cancel per the contact at the end of a contingency period, both seller and buyer have to sign off that your deposit goes back to you so if the seller is irate that you kept it off the market for a few weeks for no reason to cancel, they may be hesitant to sign it and it may take time and mediation to get it back.