To me it depends on things like your net worth, debt, and how other assets are invested.
Currently you have 25K invested in the company you work for.
If you have 100K in student loans, are a renter, and 12K in your 401K, then I would recommend exercising almost all of your options. In that case you have a much to large part of your world wrapped up in your company.
If you have 250K in your 401K, own a home and have an emergency fund with no debt then you are fine with letting it ride. You can afford to absorb a loss of 25K without wrecking your net worth.
More than likely, you are somewhere in between (just statistics speaking there). So why not exercise some of them now with the purpose of improving your financial situation? Say do a 1/3 now and when they come available.
When 401ks were first invented people put almost all of their money in their company stock. They lost just about everything when the company went down in value and were often a victim of layoffs exasperating the issue. This is akin to the same situation. Most financial advisers recommend against putting any 401K money to company stock, or at least limiting the amount.