I understand that you typically give the haircut on the day of his (Hebrew) third birthday. But if that is impractical, should it be pushed off to an earlier day or rather a later day? (People who davka do it on Lag B’Omer, are bringing there 2 year old-almost 3 year old or are bringing their 3+ year old (if Lag B’Omer isn’t the bo b’yom)?
Generally it is done bo bayom if practical. One of my sons was born during the three weeks so his upsherin was pushed off until after tisha b’av. For those who davka plan it for Lag B’omer, it is generally done before the third birthday,
Is it usual to bring him to a Rov or Rebbe to give the first cut of hair? Who else gets an honor of sniping some hair? And is the main part of the haircut done by a barber or by the father?
It depends. There are some who go to a rav; some have the father and grandfather’s take the first snips. At my youngest son’s upsherin we had a professional hair cutter do most of the haircut.
The night of the upsherin you also make a L’Chaim. What is minimally put out to eat?
Some put out light refreshments; some make a seuda (either milchigs or fleishigs). We always made a seuda for the family.
And, perhaps most importantly, you teach him some Aleph Bais from an Aleph Bina with honey. How does that work and how is that done?
And you bring him to cheder. Which cheder/class is he typically brought to? What does the rebbe usually do there? And must he be brought wrapped around with a Talis from the home till the cheder, so that he cannot see anything in between?
In my experience this is actually done at the same time. If you are makpid to go from the upsherin to the cheder, the minhag is to wrap the child in a tallis. In most chadarim a specific rebbe/class is designated for the upsherin which includes showing him the aleph beis and the rebbe usually takes a lollipop, dips it in honey, and places it on the Aleph, Mem and Sof as it spells EMES.
Hope this helps,