Like Tundra, I'm looking and thinking about opening as soon as the ice melts off my pool. I get the first part of opening done by mid April --getting the cover off, the filter running and cleaning the bottom. I let things like the ladder and drop-in steps go. As soon as the water is into the 50's you can expect algae to be in your future if you don't get chlorine in soon. Other people have different strategies, like an auxiliary pump to circulate the water then (even if it's not filtered) just to get the chlorine up.

Get chlorine in before the water has a chance to grow algae and you are OK.