Dark Tower reading order

I'm reading the series for the first time. Just about finished with The Wastelands and am planning on reading straight through the series before going on to anything else because I'm enjoying it so much.

What's the consensus on when to read The Wind Through The Keyhole? I know it's supposed to be DT 4.5, but that it was published after the original series. Suggestions for the best DT experience for a first timer? After Wizards and Glass or after The Dark Tower?

No spoilers please!!