New Buoy Applicants / Non-Minneapolis residents
By all means, do it as soon as possible. The city uses your date of application to grant you place in your selection pool. What pool you are in mostly depends on if you are a Minneapolis resident. See the menu bar on the left for the actual link. Note that the city will charge your credit card for the full buoy price upon receipt of your application. In the event that you do not get a buoy, they will refund the same amount to your card.
Returning Minneapolis Buoy Applicants
For returning buoy holders, things are not so rushed. Just as long as you get in by April 8th, you will go into the priority pool for your lake, where actual buoy assignments are drawn by lot. That part is random, but you are assured of a buoy. One of the factors that may play into your thinking is that the city will charge your credit card as soon as you apply. Me, I'd rather keep that money in my account until April.
Lake Calhoun is the biggest lake in Minneapolis, Minnesota, and part of the city's Chain of Lakes. Surrounded by city park land and circled by bike and walking trails, it is popular for many outdoor activities. The lake has an area of 401 acres (1.62 km2) and a maximum depth of 87 feet (27 m). It is also home for Keelboat Sailing lessons, hosting the Calhoun Yacht Club and the Calhoun Sailing School. The lake is popular for sailing races, canoeing, kayaking and windsurfing.