There is no instant gratification. If a person who weighs 240 pounds, out of shape, just because he started dieting and walking or attending Gym from the last few days, can not expect to look like Aishwarya Rai or to turn slim and hand some—it takes time.
The distinction should be made between how much effect a given item is having versus how much effect you notice and how much your body can stand.
The initial effects of loosing negative energies, ablation of some negative karmic thoughts may be little easier to notice as feeling of slight discomfort.
Replace them with positive thoughts, and avoid needless monkey chatter of the brain by replacing it with japa or mantra recital. This process will help in speeding up the process.
In most cases it has been observed that beads strung according to Rudraksha Science TherapyTM start showing effects in 48 hours . However this time duration may be more for some people who are less sensitive or have deeper routed issues that take time to clear.
For each Yantra or Rudraksha one adds on the body, the body has to make adjustments. Probably one may not be aware of these adjustments but they take place nonetheless. Often it is both subtle and "delayed" (meaning that you don't notice until it is "obvious"). It may be even a slight feeling of euphoria.
What isn't obvious is that our brain, chakras, Nadi systems, subtle bodies and other neuro physiological mechanisms takes a great deal of pranic energy to run and adjust. The rudrakshas or other beads, are disproportionate in their overall size compared to the rest of our body, but of course proportionate to what it does.
This additional energy fields needs time to integrate with the fields already running [your "native" fields], jewelry (some stones you already have) or items, and the energy it takes to dissipate and/or neutralize "hostile" fields such as electromagnetic, karmic attachments, self generated negative thoughts etc.
Hence some times it may takes weeks or a month or two to notice the changes. But this process can be speeded up by keeping one pure, japa, surrender and a feeling that lets one say "let your (divine) will be by will".