You'd be going back a few hours, so call it seven shifts from that. As for the aspect assessment(s), that'd be a minimum of three shifts per aspect, or more if you anticipate the Investigation roll being more difficult. So, a minimum of 10 shifts for one aspect with a difficulty of Good, or 11 shifts for one rated at Great, or 13 shifts for two Good aspects, or 15 shifts for two Great aspects. (With a consequence from Kitty and Phil, you'd have 16 shifts, so one Great and one Superb?) Then the actual ritual lets you rewind things over the past few hours and make a handful of Investigation rolls to suss out scene aspects.
Time required obviously depends on the strength of the spell. Assuming you had a 16 shift spell going and you were trying to cast it as quickly as possible without taking any stress, that'd be six exchanges worth of time (with Discipline rolls, of course), which is of course very loosely defined. Call it three minutes, give or take.