Im no expert so dont read this as advice, but you can exercise the options any time before expiry. Your total spend if you chose to exercise in this case would be 24c (4c premium + 20c strike) Since the call option is an option to buy, you would not make a profit as such, but rather purchase the shares at a discount if the stock underlying price is above 24 cents at the time.
POK Price at posting:
17.5¢ Sentiment: None Disclosure: Not Held