I tend to have a lot of my healers set up similarly so I can use muscle memory on all of them (for example, Left Trigger + B button is Glare/Broil/Malific/Dosis, and Left Bumper + X button is Dia/Biolysis/Combust and is where I put Eukrasia since I use it with Dosis to get SGE's DoT). So it may depend on where you put your buttons that are "similar" on WHM/SCH/AST if you play or played those.

I have all my damage spells (mostly on Left Trigger side) and my common use heals and CDs on my main bar, then on my second bar set is where I have the less common ones. I have Kardia on my second set on Right Trigger + Y button, with the Kardia boost skill there beside it on Right Trigger + B button because I mostly only use SGE in casual 4 man content where Kardia is set and forget. I also have LB on that second set, Sprint, and so on. I DO have Pneuma and Zoe on my first set (because otherwise I forget Pneuma exists and seeing it there on my Left Trigger + <- D-pad left reminds me it exists) and I can have it there among my DPS buttons.

I tend to have two full bars on my healers because there's no way I can play with only 16 total buttons (one crossbar "page") outside of PvP. Two pages gives you 32 buttons, which is enough for WHM and SGE, and SCH can be heavily massaged to fit, lol (AST is impossible. I've tried.)

If you need more, I could list out my entire set-up. But as I say, I think the best way is to find the similar abilities you had on your AST and put the SGE's variations in those spots. Durochola in place of Essential Dignity, Dosis in place of Malific, Diagnosis in place of Benefic, Prognosis in place of Helios, and so on and so forth. Nothing is 1-to-1, but often the bread and butter spells or spells with similar effects exist across the healers.

Hope that helps!