From the academic article, it looks like results were seen after the 4-6 week mark. Here's a quote from the article in the original post:
A series of double-blind, placebo-controlled crossover studies by Javitt and colleagues (as reported in Coyle 2004) administered 30-60 g/day of glycine to schizophrenia patients on traditional neuroleptic. Each group of patients received either placebo or glycine for 4 weeks; for the following 4 weeks, the original placebo group was given glycine as well.
Results reported a significant decrease (17%) in negative and cognitive symptoms for the glycine group, and for the placebo group following the 4-week crossover. In another crossover study by Javitt et al, the group that received glycine first (for six weeks) and then switched over to placebo (taken for another 6 weeks after a two-week washout period) maintained the improvements achieved during glycine treatment, suggesting that the therapeutic effects may be relatively enduring
I've been on sarcosine since like February 2016, just off and on for a few months. I definitely notice when i run out, my laundry piles up, my motivation drops, i don't feel like hanging out with friends or making small talk with people. I'm on it right now and my apartment is fairly clean and I'm working on my pet projects at a steady rate and i have a social life. I would recommend it.
It's like the cost of a couple fancy drinks at Starbucks and it's probably a lot better for you, too! Good luck!