What Fredo said.
FYI with my BMD card and Sony TV screen I am at 200ms with ProRes (slow screen).
NOTE not all video encoders and decoders are the same latency wise on decode, so offset may differ betweeen video formats.
And CatchinSync is what I use whenever I get worried. It is definetly good enough, and yes You will need an iphone or puchase a hardware synccheck, not sure if any are still in production though.
I find CathcinSync at least as good as my old synccheck and easier to work with.