Based on personal experience, I'd say the amounts may not be sufficient. ie, our children have often made use of Colloidal Silver over the years for colds etc, and we've observed that the sweet spot insofar as dosages go(getting results) seem to hover at/or around the 1 oz p/dose mark.
That said, I'd also add that the consensus in our home is to hold the solution under the tongue for a minimum of 5 mins. before swallowing. And that in the event of a cold or sore throat, that allowing the solution to trickle down the throat rather than to swallow it afterward seems to work best. This has proven to be the most effective method in the treatment of head colds etc.
PS. I would add that while I've never effectively cured a cold by taking anything to date. I have however, mitigated its effects to the point where it would not interfere with my work schedule or day to day activities. ie, people have often told me that they thought I had an amazing immune(at work) without ever knowing just how sick I was.