They have wave leaders for each hourly group setting the pace to get you to the start of WTF in time to achieve the target, but from there it is up to you! If you can stick with this bunch to WTF then your pacing is sorted and you have the benefit of a large group, that is if you are in the right wave for your w/kg for each duration (see OP).
Be aware that the wave leaders don’t necessarily stop for as long as advertised, so it pays to be carrying more food than needed, and sort out hydration at the stops first.
I went into it for the first time last year (and only time so far) targeting under 10hrs also. Started with the 10hr wave, but after the long descent at the start I was amongst the 9hr wave riders and cut the first stop short to follow their wave leaders when they left. Not the plan, and not necessarily a great strategy, but if you are a confident descender, there are some cheap minutes to be had. Stuck with them to WTF for an 8.46 finish.