I think you're in fine shape. Here is what I did.
I rolled in the new chain with the tensioner out, starting at the outer side of the right sprocket. Then I connected the new chain. Then I turned the crank until #1 was at TDC on the crank and made sure that the timing marks were lined up or close. Then I put the tensioner in rotated the crank a couple or turns, and re-checked the alignment of the marks. With a new chain, all three should be spot-on.
It helps to have someone hold the "tail" of the chain while you rotate the crank.
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe