It's -a- way to go. Keeping in mind that infamy absolutely wrecks foreign compete chance, even if you are fully free trade then you will want to be careful how you expand.
Local mercantile trade usually doesn't give you quite as much money but infamy isn't an issue, so if you are skilled, get a lucky break or otherwise manage to gain some momentum, you can take a small power to dizzying heights very quickly without foreign trading or even any trading at all. Of course, that will often require some heavy minting and being very vulnerable for a while but you won't be idle for those first 70 - 100 years.
For a great example, release Finland from Sweden on day 1 and try playing as them. That is what true EU3 poverty feels like. You are completely unable to trade as you stand and have no money to fund costly wars against stronger neighbours. Spending 100 years gearing yourself towards Free Trade is a way to go, and once you are trading everywhere you will have untold amounts of wealth very quickly, but expanding into the rest of Scandinavia or taking on the Russians is also an option. You could also expand while making your slider changes and once you have built a remarkable empire you can slow down, let your infamy burn away and once you have a reasonable compete chance, start trading and drowning in money.
There are almost as many ways to play EU3 as there are goals to reach. It all depends on what you want and how you want to get there.