These rules shall take effect on September 1st, 1941. They shall govern all proceedings in actions brought after they take effect, and also all further proceedings in actions then pending, except to the extent that in the opinion of the court their application in a particular action pending when the rules take effect would not be feasible or would work injustice, in which event the former procedure shall apply. All things properly done under any previously existing rule or statutes prior to the taking effect of these rules shall be treated as valid. Where citation or other process is issued and served in compliance with existing rules or laws prior to the taking effect of these rules, the party upon whom such citation or other process has been served shall have the time provided for under such previously existing rules or laws in which to comply therewith.