Great she's going well with the 4hr in the morning. Are you wanting to bring the wakeup in the morning later? If so, you may find having a 'morning nap no earlier than' time, so that you're discouraging the waking early, though if she's in bed for the night at 6, 5:30 isn't a bad wakeup time, with an 11.5hr night.
At this stage of the transition, you can sort of adjust your PM nap to lengthen/shorten your day to get you to a reasonably set bedtime if you want to.
All these options are possible, just wondering what you're wanting to aim for, as there's a lot of explaining for the various options
Is she teething at all? Just wondering if those wakings early on in the night are more likely pain or a touch of OT. How recently have you started the 4hr A times and did you do it gradually?