What are you anticipating starting with for your bottom half? FWIW, if I was starting on Mar 19 I'd have pants or convertibles and UL rain pants. Under that lower half scenario and even though I too push the temp of my sleep system with wearing bottoms I don't go very heavy on the bottoms. I have Pat Capilene 1 and 2 long bottoms but perhaps the less expensive versions I have work just as well(Hot Chillys, EMS)
Unless you want to start a jackets collection like some of us
consider a broader spectrum of environments of usage than just the AT. It helps justifying the cost. That includes being worn when not hiking at home, around town, going to work, etc.
I will not get into a synthetic verse down debate but if you might be using a jacket in potentially wetter conditions(Pacific NW, AT spring starting NOBOs, etc) synthetic has made strides in closing the gap in performance virtues compared to down. In LD serial hiking meetings one piece I see so often is a low bulk light to UL synthetic jacket. It brings a lot of versatility to the table.
Understand I come from an UL philosophy apparel approach. I want diversity, low bulk, usage of all the torso pieces as often as possible and prefer 4 layering torso than 3 layer when its cold and mixed(sloppy) conditions. I'm also a consistent moderately paced mover without long stops or many stops. My day is spent moving so I'm consistently generating warmth. When stopping for the night I'm typically in my bag/quilt in 20 mins or less. Multi use non redundancy in the kit is embraced. This plays into apparel needs. This may not be your approach. So, I'm only offering these ideas for you to be exposed to them. I'm not trying to sell you on what I do or the gear I choose. Don't take from anything I said that somehow you're doing it "wrong."
However, I do surmise you'd receive greater potential usage if you went with a lighter wt non bulky jacket in a 4 layer torso approach without having to embrace hardcore UL philosophy. What Neo LD backpackers eventually realize is that excess unnecessary wt carried can have an impact.