How long do you usually take to decide whether or not to return a skincare item?

Lately I've been trying to get better at skincare stuff (thanks a lot, skincare routine post on GT). I have started washing my face more often, going from once a day with and a gentle cleanser (Cetaphil or Neutrogena Ultra Gentle Daily Cleanser) to twice a day. Prior to my new arrival, I was using Clinique's Dramatically Different Moisturizing Lotion +, which was working okay enough, even if it did make me a bit more oily than I'd like.

Three or four days ago, I finally got my package from Ulta with my Cyber Monday order, including this Boots No.7 Protect & Perfect Intense Kit that I managed to snag on sale for $36. I've been using the night moisturizer and serum every night since it got here, and I've worn the daytime moisturizer to work once. I found I was way oilier at the end of the day when I wore it, and my face seems oilier than normal at night, too. Most concerning, though, was that this morning, I noticed several new pimples on my face as my putting on my makeup.

I'm not sure what to attribute these new pimples to, but my first instinct is definitely this set. On the other hand, maybe it's hormones? Change in skincare habits? Stress? Pillowcases?

Anyway, should I keep using the product for a little while longer to see if everything settles down, or would it be better to go ahead and return it? How long do you guys generally give a product before you give it the axe?