Taking PCAT while enrolled in Calculus..
 

I signed up to take the PCAT July 19th (this summer) but will be enrolled in Calculus 1 over the semester. The next PCAT date isn't until September and I don't want to take it when my fall courses just start.

Do you think I will be okay or is it necessary to be FINISHED with Calculus before taking the PCAT?

You may need to study ahead somewhat. I believe Calculus is 22% of the math portion, based on the outline posted on the PCAT website.

FWIW, I was never very good at Calc, and I took it a long time ago, and I still did very well on the math portion. I knew the ones that weren't simple enough to do quickly weren't worth the time. I came back to any really hard ones & did my best to give an educated guess by eliminating wrong answers. The trick is to get through all the questions so you can cherry-pick the easier ones & get the best value for your time.

It would help to look online for your basics of calculus. I did this and it helped and scored well on the math portion before I took undergrad calc. What helped though is that I took it in high school so what I found online was a good refresher. This is a decent site http://archives.math.utk.edu/visual.calculus/. There are others as well if you google them.