your spellbook, book of shadows, whatever is as darkautumn said, anything you can log your sacred arts in. I actualy have several tomes appointed to different things. (i.e. astral journal, magical notes, spells, rituals, gem, candle, color, herbs, etc.) When you designate that book only write in it concerning your works tho. Most people I know wrap their tools in black silk. hard to find I know, but black for banishing and silk generaly staves off negative energies. if you cant find that, get a cedar box at a craft shop, cedar is good for purification and can keep it safe. just try to keep it out of the reach of others because tools work better with just your vibrations.
if you can remember it perfectly all the better. notes are also helpful to go back to in twenty years and see how well you've progressed or for those who follow after you to learn from. ultimatly, no tome-tool-or words are nessicary. all magic comes down to your own energy and the will of the gods
No you don't have to start it on a full moon. I honestly don't think it makes any difference. You can use a notebook for all I care. It doesn't matter. I write spells on sticks notes and add them to my spell book whenever I have the time.
A spell book is known historically as a BOOK OF SHADOWS. It is called that to reference Shadows not to evil, but past. So it is a book of a praticioners past. It is recommended to start a book on a certian phase of a moon to make it more powerful, but as others have posted, a book of shadows is never done. As a past, it should be only finished when the coven/practitioner has passed or passed the book on. Do not worry about deadlines. There are none. You do not HAVE to start a book of shadows on a certain day. Just be sure it is only for your magic, it is kept in a safe place and you should keep it from prying eyes. Write notes, incantations, ingredient uses, anything and everything that helps in your magic, but mostly spells you have used, how they have worked, etc. Hope this helped!
"Book of Shadows" is actually a relatively new term that came from Gardner himself. The older word for books of magic is usually "Grimoire" or "Receipt Book" (believe it or not...it was a mis-spelling of "Recipe Book" by Cunningfolk).
As for finishing it---mine's still getting new info inputted after over 2 decades of study and practice.
I chose to write mine on the dark moon, symbolizing new beginning. By the way just to people in general, a blessing of a book of shadows is just a way to make you feel it's special and enhcanted, I personally just kept adding spells to it and believeing it was enchanted and I get an abnormal feeling whenever I look at it (and I don't think it's delusion either) so in my OPINION you don't need a blessing ritual. But my view's subjective, so do what you want.