I'd definitely agree. Do a trial first. Some nappies fit some babies, and some fit others. Sadly some are pretty useless anyway! If you have tried out lots first, you'll be quite sure you buy something which will fit your LO, and will also fit your life style and washing/drying facilities.
Also check out whether your council has a nappy initiative, as you may get some financial help to buy cloth nappies.
Here's a list of councils which have schemes. If your council is listed, click on it, and it will take you through to the details