+1 to above, seems like solid advice. Not enough time for 3L that has fermented out. You're going to want to have enough yeast for a 1.087, so I wouldn't rush it.
I'd either go 2 dry packets for the big gravity brew.
Or get a starter going immediately for the 1.063 brew. Maybe go 2 L and direct pitch the whole thing as you likely won't have time to ferment out, cold crash, and decant. 2L is about the largest starter I direct pitch, as anything larger will really start to influence your final brew. This will still be underpitching some, but not by a large amount.
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