When you change your routine, skin takes time to adjust. A new product means a different texture and ingredient profile; skin responds gradually, not immediately. First-day impressions rarely reflect the final result.
As a general rule, allow at least one skin renewal cycle — about 4 weeks — to evaluate a product. Deciding sooner may be unfair to it. Of course, with clear discomfort (burning, itching, redness) there is no need to wait; discontinuing is right.
To ease the transition: add new products one at a time, patch test first, use less frequently at the start and increase gradually, and keep the rest of your routine unchanged.