Season 4 NA:

What
When
Season 4 [NA] Signups Open
3rd of November
Season 4 [NA] Signups Close
9th of February (Subject to change)
Season 4 [NA] Seeding
10th of February (Subject to change)
Season 4 [NA] Round 1 starts
16th of February
Season 4 [NA] Season 4 [NA] Round 8 starts (last round)
12th of April
Last dat to submit replays
17th of April
Season 4 [NA] Draw Show
19th of April
Season 4 [NA] Playoff Group Stage starts
20th of April
Season 4 [NA] Epic Cup Group Stage
20th of April - 16th of May
Season 4 [NA] Epic Cup Finals
17th of May
Season 4 [NA] Legendary and Mythic Group Stage
20th of April - 22nd of May
Season 4 [NA] Legendary Cup Finals
23rd of May
Season 4 [NA] Mythic Championship Finals
24th of May
Playoff Ends
24th of May

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



Season 3 NA:

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
21st 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
Epic Cup Group Stage - Divisions 3 & 4
4th of November - 29th of November
Legendary Cup Group Stage - Division 2
4th of November - 5th of December
Mythic Championship Group Stage - Division 1
4th of November - 6th of December
Epic Cup Finals - Divisions 3 & 4
1st of December at 1pm PST
Legendary Cup Finals - Division 2
7th of December at 1pm PST
Mythic Championship Finals - Division 1
8th of December at 1pm PST
Season 3 [NA] Playoffs end
8th of December