From a halachic viewpoint, what is the proper age for a boy to meet one's potential wife nowadays? (i.e. dating)
According to the Minchas Chinuch (or perhaps it is the Sefer Hachinuch), the mitzva of פרו ורבו only applies at the age of 18, as in the mishna in Avos 5:22. The Gemara in Kidushin 30a is somewhat critical of someone that waits beyond the age of 22 or 24; however, the exact age depends on the emotional maturity of the child, as per חנוך לנער על פי דרכו, "Educate the youth according to his way" (Mishlei 22:6).
So, to answer your question, the exact age depends on the individual, and generally varies between 18 and 24 to begin the search. Obviously, one cannot be held accountable for marrying late if the search took a long time (אונס רחמנא פטריה, the Torah does not hold one liable for circumstances beyond his control).
Kidushin 29b discusses the ramifications of one who is learning, perhaps abroad, and Rashi and Tosafos have different interpretations of under which circumstances one could marry later because of learning Torah. (I don't believe this would apply to non-Torah higher education, which is not a mitzva per se.)