Season 11 EU:

What	When
Season 11 [EU] Signups Open	13th of October (20:00 CEST)
Season 11 [EU] Signups Close	17th of November (23:59 CEST)
Season 11 [EU] Seeding	18th of November
Season 11 [EU] Round 1 starts	2nd of December
Season 11 [EU] Round 3 starts	16th of December
Season 11 [EU] Christmas break	2 weeks of no matchmaking
Season 11 [EU] Round 4 starts	6th of January
Season 11 [EU] Round 10 starts (last round)	17th of February
Season 11 [EU] Last date to play regular season games	28th of February
Season 11 [EU] Draw Show	1st of March
Season 11 [EU] Playoff Group Stage starts	2nd of March
Season 11 [EU] Playoffs end	29th of March

Season 10 EU:

What	When
Season 10 [EU] Signups Open	9th of June (20:00 CEST)
Season 10 [EU] Signups Close	14th of July (23:59 CEST)
Season 10 [EU] Seeding	15th of July
Season 10 [EU] Round 1 starts	29th of July
Season 10 [EU] Last round (10) starts	30th of September
Season 10 [EU] Last date to play regular season games	11th of October
Season 10 [EU] Draw Show	13th of October
Season 10 [EU] Playoff Group Stage starts	14th of October
Season 10 [EU] Playoffs end	10th of November

What	When
Season 3 [NA] Signups Open	23rd of June - Announced on the Draw Show
Season 3 [NA] Signups Close	4th of August (11:59 pm EST/8:59 pm PST)
Season 3 [NA] Seeding	5th of August
Season 3 [NA] Round 1 starts	2nd of September
Season 3 [NA] Last round (8) starts	21 of October
Season 3 [NA] Last date to play regular season games	1st of November
Season 3 [NA] Draw Show	3rd of November
Season 3 [NA] Playoff Group Stage starts	4th of November
Season 3 [NA] Playoffs end	TBD