Rather than using “pv0=” to set a Salesforce report filter dynamically with Nintex Drawloop Dcoument Generation, you will need to use &quarter_q=custom which will set the date range of the report to custom. You will then need to use&coldt_s=01/01/2018 and &coldt_e=01/02/2018 to set the start and end date of the Salesforce report filter.