I just received an email from Placemakers (as a holder of a KnowHow card) saying they are doing double 10% (20%) off any purchase from 1 Feb 2019 to 10 Feb 2019.
The first 10% appears to be a general KnowHow discount available at all times on purchases over $100, but the second 10% is time limited, and seems to be 20% of any purchase no matter the value.
Not sure if this is only for selected KnowHow members, or everyone (I haven't shopped there in a while, so it might be to get me back there), nor can I tell if you can sign up today, and get the extra discount tomorrow, but worth a try if you are looking at any reasonably large purchases over the next week or so.