72:9 One should not make a habit of doing work on Friday after "mincha ketana," which, as we have discussed, is nine and a half shaos zemanios after sunrise (shaos zemanios - "seasonal hours" - being one-twelfth of the daylight hours, varying in length depending on the time of year. Mishnah Brurah 251:3 cites the opinion that prohibits such work after mincha gedolah, which is three hours earlier, but concludes that one may rely on the more lenient opinion). One may, however, do occasional work at this time, as well as things that are necessary for Shabbos. One may not repair a friend's clothes for pay at this time, though a needy person who wants to earn some money for his Shabbos needs is permitted to work all day long similar to the way one may work on Chol HaMoed. (This is true even if he already has the bare necessities and only wants to buy things that make Shabbos nicer - MB 251:5.) One Jew may cut another's hair all day on Friday, even if he is a professional barber who is being paid for his services, because the haircut is clearly being given at this time in honor of Shabbos. Stores should close at least an hour before Shabbos.
72:10 It is a mitzvah on Friday afternoons from nine hours (shaos zemanios) and on to avoid having a meal, even one he normally has on weekdays at that time. (If one started a meal, he is not obligated break it off - MB 249:16. In the winter, when days are shorter, it is advisable not to eat a meal even earlier if one has reason to suspect that it will ruin his appetite - MB 249:17.) When it comes to a meal that one does not normally have on a weekday, even if it is a meal for a mitzvah, if at all possible, it should be held on another day and not on Friday, even in the morning. If a meal for a mitzvah has a set day, like a bris or a pidyon haben, then it may be held on Friday, though it is appropriate to make it early in the morning and not to overdo it. (A bris that was postponed may be held on Friday because it is still a mitzvah to do so as soon as possible - MB 249:12.) It goes without saying that one should not eat too much because a person is supposed to eat his Shabbos meal with an appetite.