kutimo

One root covers both the private habit and the shared custom, and context sorts out which is meant. The really useful derivative is the adverb kutime, meaning usually, which turns up in nearly every paragraph of ordinary prose. The verb kutimi means to be in the habit of doing something, so mi kutimas frue vekiĝi says I usually wake early. Do not read it as customising anything. Kutimiĝi al is to get used to something, and it takes al, not the accusative.