Eingewöhnung — getting used to something. It is also the word for a small child’s first weeks at daycare.
Einarbeitung — being worked into a job. Companies speak of the Einarbeitungszeit, the working-in period, and the Einarbeitungsplan, the onboarding plan.
Sich einleben — to live one’s way into a new place. Duden explains it as getting used to new surroundings and becoming at home in them.
Seinen Einstand geben — to give one’s entry. A new colleague marks the start in a job with a small celebration or a round of drinks. Duden marks this use as mainly southern German and Austrian.
Schonfrist — a period of protection, a time of grace before something unpleasant begins.
Aller Anfang ist schwer — every beginning is hard.