komencanto

This is the textbook participial noun, and it is the example La Parolanto is built around. Take komenci, swap the infinitive -i for the present active participle -ant-, add -o, and you have the person who is doing the beginning. Nothing is memorised: parolanto is the one speaking, laboranto the one working, komencanto the one starting out.

The tense in the middle is doing real work. Komencinto would be somebody who has already begun and is past it; komenconto somebody about to start. English needs a relative clause for both, which is why the pattern feels like a trick the first few times and then stops feeling like anything.

Do not reach for lernanto instead. It was built as one who is learning, but usage has settled it on pupil at a school, with studento for the university version. And -ist- names a trade rather than a phase, so instruisto is a teacher by profession while instruanto is whoever happens to be teaching this afternoon. Beginner is a phase, so -ant- is right, and the word is a compliment: nobody stays a komencanto.