I would put your collection in some kind of order first. It can alphabetical, divided by publisher, divided by character, whatever works for you. Putting the books into CB won't be an overnight process and having some system in place will make it a lot easier to step away whether it is for a day or two or a few months and get right back into the groove when you return.
Creating a space is a great thing to do if you can. Setting up on the dining room table is fine until you have to clear it off for dinner. If you can have some little corner to yourself, you can bring in a box at a time and get them entered. Assuming you are using regular comic boxes, whether the long ones or short ones, find a divider of some kind. I taped two backing boards together so they stood out above the books by a couple of inches. Put that divider at the back of the box, behind all of the books, then as you enter books, move them behind the divider. This keeps the books in a single box and in the order you started with while making it clear what has and has not been entered.
Bar code scanner or no, if you're having trouble finding a book in CB, you can enter the UPC numbers by hand. It may be slow but if it's only for the random difficult to find book, it works really well. Given that your collecting took off in the 80s and 90s, it is possible that you will have some small press stuff that is either not in the system or is difficult to find. That's a great time to post on the forums to ask where they might be.
Don't get discouraged! That's a lot of books to enter and will take time a regular life pushes comics out from time to time. You will get it done!