Give it a good go - you need at least 3 months before judging it. This is especially true for anti-ageing products.
The reason is that changes in collagen metabolism (in the dermis) take around 3 months to happen. Prior to this, you might see other changes already such as an improvement in skin hydration, which often already happens after a few days.
Further to this, improvements in skin glow caused by increased cell turnover in the epidermis might become visible after around one month already. However, real anti-ageing benefits with increased collagen production will take 2-3 months. Of course the results will continue to improve beyond 3 months.
The only reason to stop a skincare regime earlier than 3 months might be if there are tolerance issues, for example if you react with a rash to the product, in which case you should stop immediately.