You might want to pose this Question in the Lawn Care forum. May get a quicker response.

Here is a link that might be useful: Lawn Care

And what the heck does "playing with the lawn" mean?

Playing on the lawn---he**, you can do that anytime--depends on whether you wish to kill what's there or not or whether you want to create a mudbath after a spring rain.

Kill weeds? ..cant do that until they are growing actively---that means in cold Ontario...to about the end of May to mid October.
If its mowing you are asking about....that depends on how high you let it grow but essentially should be cut when its more than 3" high.

Put the hockey sticks away, kill the grubs with football/baseball cleats.