Is it OK to use my company name/logo in commerce before trademarking? Or would it be better to get official trademark before using it?

You should without a doubt, file for trademark protection before “going public” with your logo. Your logo is your intellectual property and the only way to safeguard it from being used by others without permission is to get it protected by The US Patent and Trademark Office. Whether you apply for protection via copyright (which covers writings, music, and works of art) or trademark (which covers a word, name, symbol, design, or any combination) depends on how much creativity went into the logo. In order for a work to have copyright protection, it must reach a requisite level of creativity. Some companies looking to protect a logo file for both. The US Patent and Trademark Office has all the information you need to get protected: http://www.uspto.gov/smallbusiness/trademarks/registering.html