Are you asking about N0 or just EV? Because you could be over 3SD away from EV in as few as 12 or 13 hands (depending on your advantage and rules). Assuming a $100 bet size with a 1% advantage and an SD of 1.16, -3SD/+3SD at 12 hands would be -$1193.51/$1217.51 and at 13 hands would be -$1241.73/$1267.73. So if you sat down and lost your first 12 hands, your -$1200 result would be more than 3SD away from EV. Likewise if you won your first 13 hands, your +$1300 result would be more than 3SD away from EV.
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