We have seven top winners and can set up three more in diamonds (unless trumps fall 5-0).
So, win the first trick, draw trumps, and play on diamonds.
Ruffing a spade in hand with the long trumps cannot gain a trick, and weakens our trump control. As the hands lie, it might be catastrophic, because trumps fall 4-1, and we have still to lose ♦A to establish the suit. If we realize our mistake and try to set up the diamonds while there is still a trump in dummy, North can hold up ♦A until the second round, and lead a third round for partner to ruff.
