Entering mid shoe without knowing count?

Assume the game is 8 deck total. DAS, 75 pen (6 out of 8 decks). I come in mid shoe without back counting and 2 decks have already been played. That now leaves a total of 6 decks in the shoe, 4 of which is playable (2 decks still are behind cutcard). How do I play this game?

Do I play it as if it is a 6 deck game with 66% pen and start my counting at 0?

Do I simply play it as an 8 deck game with still 75% pen?