A primary consideration is to determine if you are using analog or digital outboard gear.
If you are using all analog outboard gear the round trip latency is compensated for automatically by SONAR. (with the caveat that many ASIO drivers need to use the manual input in the SONAR audio options dialog)
If you are using digital effects like multi-fx or reverbs you can also compensate for their latency which is usually a minimum of 1.2ms.
SONAR has some features for that... but I don't have any digital outboard so I don't know much about it.
You may also just nudge manually.
Additionally, some aficionados of digital outboard like the latency delay and relate it to the same effect they have in live play.
It easier to mix with all the other stuff if the delay is compensated for.
A good place to start is too patch up a loop and then do a round trip ping test to judge your system latency and correction and then you go from there.
best regards,
mike