If you're specifically asking whether external first, internal later is the best way to go for aikido, then I don't know if there's a universal right answer. A handful of aikido dojo have largely or completely switched to an IP-centric training model within the past few years or months, and so time will tell how the students introduced to and coming up in aikido via such models turn out (maybe some others will chime in on that). Something as foundational to aikido as Shomen-uchi Ikkyo/Ikkajo is relatively complex for a beginner from a conventional or IT perspective.
Also, don't Ki Aikido folks start internal training from the get-go?
Yep and I've long been in favor of an integrated approach. To use pedagogical models from outside martial arts....best foreign language learning I've experienced integrates getting you listening/talking immediately PLUS learning alphabet, sentence structure, etc immediately...when I've taught beginning sewing and beginning painting, I have people immediately work on basic hands-on projects AND do exercises that build on principles, like examining the phenomenon of color in the natural world or experiencing different fiber and fabric types.