This is another question I have been asked thousands of times. Generally, it depends on the situation. If you file first, you do by definition control the timing of the commencement of the action. This can and should be part of your divorce planning strategy, but is not an overriding consideration.
Florida is a no fault state. Filing first does not make you look good or bad to the court, so no brownie points either way.
The filing of the petition establishes the date that the court will use to determine marital assets and liabilities, so if you win the lottery the day before the petition is filed, the winnings will be divided 50-50, but if you file and win the next day, the winning ticket will be non-marital in nature and will most likely not be split. (Although one can argue the dollar used to buy the ticket was marital so the ticket is marital as well– there are always arguments and counter arguments).
The filing date also establishes the number of years of marriage for purposes of determining alimony. For instance, if you file a day before your 17th wedding anniversary, under the new alimony statute, you may avoid (or be excluded from) paying (or receiving) any permanent alimony. If you file on your 17th wedding anniversary or after, you may be facing (or be awarded) a lifetime of paying (or receiving) lifetime alimony. So the payor spouse would want to file first, the payee spouse would want to hold off. Learn more about alimony.
The petitioner also presents his or her case first at trial, and has rebuttal time at the conclusion of the respondent’s case. People naturally remember the first and last parts of a sequence of facts, and judges are no exception, so the petitioner has some advantage there. Going first at trial may be a mixed blessing though, as going second allows the respondent to adjust his or her case on the fly.
So the bottom line is that each case is different and the urban legend that you ALWAYS have to file first is not necessarily correct.