Timing Swarms in Ontario

[fshrgy99]

Greetings fellow Ontario Beeks!

My girls appear to have survived beautifully through the winter and have been actively gathering pollen on the (handful of) days that were 10 degrees or better. Although it snowed again last night I have the feeling that they are itching to swarm at the first sign sustained warm weather.
I'd really like to time my splits to forestall swarming but don't want to do it before there are mature drones to fertilize new queens.

Have any other Ontario members seen signs of swarming or drones in their hives?