To fix an AC you must spend a seasion and 1P of vis.
But you can do other things or Laboratory activities in that season?
An fix 2 or more AC?
I would assume that fixing the connection takes up the season, just like any other major lab activity, and you don't do anything else. Not sure if you'd even get exposure XP toward magic theory.
I would be kind enough to allow exposure in Magic Theory (the entry for Laboratory Work reads "Magic Theory, Supernatural Abilities used, Arts used"; so the Magic Theory need not be used to gain xp).
Since you have no Lab Total, you cannot use the 'Multiple Laboratory Activites' rule. It's a lacuna in the rules, by the rules as written it isn't clear how you can shorten the time it takes to fix an arcane connection. You can go with wulfenbach and decide that since the rules do not stipulate how you can shorten it you simply can't, or establish some house rule.
I think a reasonable house rule would be 1 arcane connection per 3 in Magic Theory. This way a young magus can only fix 1, and no Arts are involved as there is no Lab Total. Like with other multiple activities, all activities must be of the same type (fixing arcane connections).
Since you are limited in the maximum number of pawn of usable vis in a season (magic theory x2) and since to fix an arcane connection you need of 1 pawn of vis, I think that in a season you can fix a number of arcane connections as your magic theory x2.