My rule of thumb for dewinterizing in SE Michigan has been: I wait until we've had at least a weeks worth of overnight lows above freezing and the 10 day forecast does not include any below freezing temps in it.
Which means this weekend and next weekend are out due to the freezing temps forecast for this weekend.
I had good luck following this rule with our previous campers, but since we've done some "winter" camping in the Axis (e.g. driving it to FL in December) I now simply just wait until just prior to our first camping trip. Thus I won't dewinterize until mid April or so and will do so the day before we leave for our first weekend camping trip (which usually is a short spring shakedown trip to someplace near by like Frankenmuth).
The water system in the Axis is so "small" that it really only takes 10-20 minutes to dewinterize (sanitizing does add a bit to that time though).