If you want a reasonable seat, aim to be at the check-in desk (ie allow extra time to queue) at least 3 hours prior to Scheduled Departure Time.
If you're not fussed about seating and don't mind being wedged between other people, stay in bed a wee while longer - but if you're at the desk after STD -120 mins, you'll likely get to meet new friends who keep digging you with elbows during the meal!
As has been said already, Summer's here and so are the queues!!! All airlines state the same thing when it comes to minimum check-in times:
Passengers must present themselves in sufficient time, allowing for check-in queues, for all transactions to be completed no later than 90 minutes (long-haul) and 60 mins (short haul) prior to departure. (The fact that the desk closes at -60 and -30 respectively, is to allow check-in staff to complete their bits and pieces, NOT for lazy so and sos to get an extra few minutes kip!)
Arrive at the airport late at your peril!