Since most of the beneficial bacteria that keeps our tank "cycled" is located in the filter, I would suggest setting the filter up anyways or getting one that is known to have a small current or has an adjustable flow.
It would be easy to baffle your filter you have now so you don't have to purchase another one.
Someone has mentioned how to baffle the outflow, if the intake is just a tube that sucks in water, you can buy cheap sponges and either shove them inside the tube, or get a pre-filter sponge which fit right onto the outside of the tube. They look like this:
They are made for a Fluval filter, but they fit perfectly on both my Tetra Whisper PF10 and my Top Fin 10. You can always cut the sponges to make them fit the way you want them to, though mine required no cutting at all.
Make sure to read up on the Nitrogen cycle and keeping your beneficial bacteria happy and healthy so they can remove the dangerous Ammonia and Nitrites.