Q. I was eating matza for lunch on a Friday afternoon when it was still six hours before Shabbos. Some guy starts screaming at me that I am being Mechallel Shabbos (desecrating Shabbos), as one may not eat matza then. What is the correct response?

A. Shulchan Aruch (O.H. 249: 2) rules the eating a bread meal one is accustomed to eat regularly every day, can in principle be eaten any time on Friday too, yet it is a mitzva to avoid after 3.30 PM (Zemanius hours).

Mishna Berura (ibid. 15)) explains that if someone eats without ‘Kevios Seuda’ or a meal that is not prepared and cooked as being important or significant as for a special ocacion, but just is a regular weekday meal, it can in principle be eaten the complete day, yet if it may affect the appetite for the Shabbos Seuda it is a mitzva to avoid at that time.
Horav Shlomo Miller’s Shlit’a opinion is similar.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller, Horav Dovid Pam, Horav Aharon Miller and Horav Chanoch Ehrentreu and Horav Kalman Ochs Shlit’a