What does preparation for a first confession, then the actual confession itself involve?
For your first confession, you'll want to set aside some time to sit down and go back over your life, trying to remember every sin that you have committed. Many people find it useful to actually write down notes as they do so to ensure that you are as comprehensive as possible.
For the confession itself, you go to where the priest is taking confession. Venerate the icon (cross, gospel). Some people kneel, some people don't (not sure if this is a cultural or a purely personal variation). The priest will say some prepatory prayers then put his sticharion over your head. At that point just start talking, listing all the sins you have been able to remember. Depending on the priest, he may just let you talk until you run out of things to say or he may break in with questions if he feels there is something you need to explore more fully. When you reach the end, say something to let him know that you are done (and not just pausing to try to remember something else or gather courage to say something particularly bad). The priest will then say something to you--it may be brief, it may be quite detailed with follow-up questions and instructions on things to do between now and your next confession. For your first confession, which will presumably be before your reception, you will then simply get a blessing from the priest and kiss his hand--after you are received, when you go to confession, once you are done the priest will pray a prayer of absolution over you. When he finishes that, you kiss his hand, venerate the icon again and then go wa
How much detail do you go into during confession?
Not too much. You want to go into enough detail that it's clear what your sin is. And if the sin is part of a complex of things ("I got mad because someone hurt my pride") then you want to go into that chain. But you don't want to dwell on the details: i.e., say "I gossiped" but don't then add 'about x and her relationship with y'; or I committed fornication but then don't add where and with whom and how many times and if it was good or not, etc. If something is a pattern, then you can confess the pattern without going into the specifics of every single time you committed that sin.
--things you specifically want to avoid doing are
a) don't try to justify the sins. If you said something hurtful to someone, say that--but don't go into what they did that caused you to do so.
b) don't ever specifically identify another person in your confession--say 'family member' not 'my sister Mary', 'another parishoner' not 'George'
c) don't confess other people's sins.
How do you know you're truly repentant of what you're confessing?
It's like 'Lord, I believe, help my unbelief'. Don't worry about whether you are *truly* repentant. Confess what you know you should confess, feel as repentant as you can and pray to God that He will guide you ever deeper into 'true repentance'. As a neophyte, you will simply not be capable of being as repentant as you may be 20 years from now after 20 years of confession and ascesis and participation in the sacramental life of the Church. That's okay, do what you can and just keep striving to improve and God will take care of the rest.
What if afterwards, you remember a glaring sin that should've been aired at your first confession?
This is one reason some people find it useful to write things down before going to confession (then burn the paper afterwards
). If you have something you know you should confess and you deliberately don't do so, then that's bad and at your next confession you need to confess both sins--the original one and then the hiding it. But if you just plain forget, then that's covered by the prayer of absolution (or by baptism in the case of your first confession). If it's something that weighs on you, you can certainly bring it up at your next confession.
For those who converted to Orthodoxy as adults from a non-confessional Christian tradition - what did you do and how long did it take to prepare for confession? How long did the confession itself take? What happened afterwards?
I converted as an adult from a non-confessional tradition, but that was 20 years ago. I had several weeks to prepare, but most of the preparation was done in several sessions that I set aside an hour or two at a time to just think through my life--and when I got to the end of the time I originally set aside, I realized I was going to need to set aside more time.
As for the confession itself, I have no idea how long it took--and I don't think I realized it even at the time. In the end, it's going to take as long as it takes.
Afterward... I felt like someone had taken an iron bar and beaten me all over.
Any other advice for a would-be penitent before, during and after confession?
Just be honest and open--and that includes about your ignorance. If you are in the middle of confession and something occurs to you that you are not sure if you should say it or not, just tell your priest that "I'm not sure if I should say this...." and let him guide you.