8.43 per kilometreis a really decent pace for C25K ThereGoesTheAlarm. It really isn't about pace though, just how long you can run for non-stop.
Are you generally fit and do sports? If so, a runner will often have their first kilometre or two as a "warm up". So go straight into running but accept that the pace of your first 10 minutes or so will be slower than once you "get into your stride". So running is the warm up, if you see what I mean.
But there is definate value in easing your muscles into strenuous exercise, which is why the warm up is good. But if you're fit and healthy enough then your muscles can go straight into a jog. Just know that you're pace is going to be lower.
For an experienced runner, the main purpose of a warm up (be it a warm up walk, jog or run) before a main run is so that you are ready to run fast from the moment you start your proper run. So it's for those chasing fast paces and personal best times.
From your last post I see you are interested in your pace and time/distance (even though you don't need to be) so it might be better for you to keep the warm up. Why not make it a slow jog or very fast walk to get your heart rate up, so you don't get cold or feel it's wasting your time? Then you'll run better once the "proper run" starts.
But the bottom line is that the warm up is less important than the cool down (Which is never recommend you skip). But skipping the warm up might make the initial 10 mins if your run feel harder work and be a slower pace