Probably July ... (last year the window was announced on 7th July that it'll open on 8th July) ... after the relocation ends, they'd give out the value gold their seats ... next week they're sorting the supporters clubs with their requests etc. then they'd wait till 16th June fixtures are announced and sell all the more Cityzen memberships telling them that's the only way to buy any early tickets (or for big games), around end of June then those individual fixtures go on sale ... then when lots have gotten on all these, they'd quietly announce a day for Cityzens to get some seasoncards, which will be only in L1 and L3 on east and colin bell and maybe in family stand, none in south stand, none in L2 anywhere (at least this is what happened last year) ... that window lasted about a half hour and only singles were spread around mostly ... last year though they had a second window in August first week as well when they said a few more limited nos. are available for Cityzens to pick up, that second window lasted about 10 mins.
Good luck!
Edit: Oh, and yes you can buy for a second person as long as they are linked in Friends & Family and also have a STAR in front of their name showing they're in your City Family Group as well.