I suppose that I should admit right here in the beginning that I am biased and that I believe that disseminating your viewpoint and participating in the ongoing topical discussions in your industry or market segment is always a tremendous benefit to a company. Really, I can't imagine why any company wouldn't be as involved as they could possibly mange in the online world; it's where your current and future customers are already devoting their time and attention.

Your first question is about whether you should edit or delete critical or negative comments or feedback on your blog, and I have to say that I err on the side of saying yes, though in very specific circumstances. Let me lead up to my explanation, though...

If you are blogging, you will inevitably garner spam comments. You know what I'm talking about, they're either overtly spam (e.g., "Check out our new online casino at http://blah blah blah") or perhaps a bit more subtle ("Thank you for good point. We sell related product at http://blah blah blah") or, sometimes, quite subtle as they actually have taken the time to participate in your discussion with a meaningful and useful contribution, they just went a bit far with their eleven line "signature" in the comment.

Generally, I delete the former two types of spam summarily and will trim down the self-serving blather at the end of otherwise good comments in the latter case. I figure that if they already have the URL or address of their business in the "URL" field of the comment, people can click on their name and learn more about their business or online presence anyway, so it's not removing all traces, just making it a bit more succinct.

In addition to those, you'll possibly have just stupid comments, where they are likely kids who have learned how to spell various obscenities and are therefore trying to use as many of them as possible. Not good. I delete those too: I don't like people talking that way, and I don't like reading that kind of commentary on my (or any other) blog.

Finally, in addition to the gems, the smart, useful and interesting comments you hope to have left on your blog entries, you'll also have criticism of your company, service, product or personnel left either by genuine customers or competitors masquerading as customers. My opinion is that you should leave most of those intact and respond to them professionally and directly.

Now, if someone leaves a comment for me like "this site sucks and you're so gay" (yes, I get those) then I just delete it. That's not a useful criticism. But a comment like "this article is ridiculously out of date. Why have it online if you can't keep it current?" is a helpful critique and one that I endeavor to address as soon as possible, both by trying to fix the identified issue and by leaving a subsequent comment about why the situation arises and how I'm addressing it.

If it's a legitimate criticism from a competitor, well, if it's legit, then it's worth retaining and addressing. If you and I both own restaurants and you sneak onto my site as "joe customer" and complain that I don't have cheesecake as a dessert while 'Mike's down the street' does, then I'd seriously consider adding that to the menu even if I knew you were a shill because, just maybe, customers might want it too. (Easy to test: have a half-dozen in the freezer and feature it as a special for a week)

If they're just trashing your business, then again it doesn't matter if it's from a competitor or not. Comments like "you suck and your business sucks too" aren't worth keeping, in my opinion, whether they're from your Mom (hopefully not!) or your most aggressive competitor.

Finally, your bonus question is when to start blogging for your business, and I would say that the best answer is start writing your business blog entries immediately. It doesn't really matter if you've been in business for six months or aren't opening the doors for another eight weeks: your blog is a way to get noticed, to gain visibility, to engage your current and future customers and to participate in the ongoing discussion in your industry. If you're trying to gain visibility for both yourself and your business, why wouldn't you get started as soon as possible?

Which reminds me, I need to go write something for my own business blog too. :-)