Time is the number one requirement for cruising the faster you try to go the more unsafe and stressful your trip will be 60ft or not they all sink. Little ones will enjoy swimming and building sand castles on South pacific islands waiting for a nice weather window so will you.
Aim to cross the equator after 1 May. This means you should leave home in the first week of April if going fairly direct. If you want to stop in Mexico on the way through you might leave some time in March but the first week at sea will be cold.
At the other end, you want to land some time in November. You need to be in Bundaberg or anywhere South.