No, not necessary. The arrival date is the earliest you are to arrive, you can therefore arrive later. The departure date is the last day you have, unless you get an extension.
For example: You apply for a 1-month visa and submit your arrival date as Jan 1, 2011, the visa letter will be valid from Jan 1, 2011 – Feb 1, 2011. You can arrive anytime between Jan 1 – Feb 1 but must leave the country by Feb 1, 2011.”