I'm sure it's different for everyone, but it took me several months to "acclimate" to aerobars. I used them on two bikes for about a year, removed them a few months ago, and it's seemingly talking several months to re-acclimate to not using them again.
I know that I had to move my saddle forward several inches to get comfortable in the aerobars for an extended period of time. If the OP's saddle is setup for "normal" riding, that would absolutely explain the discomfort in the glutes.
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