Is this the proper way to do a 12x400m speed workout? Help on pacing please

The rest between intervals should be labeled "Recover" not "Cool Down" and the mile at the end should be "Cool Down". The pace target should be for a mile, not for the time of the interval. At that pace you are running ~32 second 400m. Your pace target should probably be about 8:12-8:52 if your target is 2:03-2:13 for 400m. You are right that it's good to have some room on either side, though be prepared for the pace alert to come up, at least at the beginning of the interval due to GPS lag. Oh, and once you have everything set, remember to hit "Send to Device" and then sync your 235.

One possible suggestion is to maybe change your warm up and cool down to "Until Lap Button". That way you can do additional warm up if you want and it won't actually start the intervals until you are ready and press the lap button. It would also let you cool down for more if you want without it ending the workout on you once you hit 1 mile. That's how I usually set up my intervals since I would sometimes vary my warm ups and cool downs.

That looks like a tough workout, have fun!

Please see the edit I made regarding your pace target. I think you may have it set way too fast!

So that's what I was confused about...the 400m target pace....my target pace for the 400m is 2:08, wasn't sure if that was what I should set it at, or I need to range that up to a mile pace setting..

the mile pace target should be 8:32

think this may work

Yep, that looks like it'll give you the workout you want. Keep in mind that after the 1 mile warmup is finished it will go immediately into the first interval (and pop up a message telling you to go) and that after the 1 mile cool-down it will automatically end the activity so be ready for those. Also, if you ever need to skip a step for whatever reason, the lap key will end the current step and advance to the next one no matter where you are in the current step.

Thanks a bunch for your help & advice, I'll try this out in a week and report back with results ;)