Interesting - I have a bottle of Prazipro that says treat every 48 hours (but that is wrong). I went online and the Hikari web site has (mostly) good instructions. I don't know if I misread the one of the bottle or if they just changed them or what, but you can follow these:
Do not stop filtration, but remove activated carbon and stop foam-fractionation (protein skimming) and UV sterilization-failure to do so will render product ineffective. SHAKE VIGOROUSLY before use. Measure Liquid PraziPro® at the rate of one (1) teaspoon (~5mL) per 20 (76L) gallons of water to be treated (one [1] fl. oz. [29.5 mL] per 120 gallons [454L]). Care should be taken to treat the exact amount of water in the system. This means deductions for substrate, rock or coral and any other internal equipment is necessary. You can calculate the amount of water in your aquarium by taking a measurement of the length x width x depth of the area with water and dividing by 231 for approximate volume. This produces a concentration of 2.5 mg/L. Distribute the proper amount around the edge of the pond or aquarium or directly in to the filter box to achieve the best overall distribution. A single treatment lasting 5-7 days may be sufficient. Retreat as necessary, but no more than once every 3 days. May be used as a preventative, at the standard dosage, when disease is likely. Do not use with any other drugs or disease treatments. May cause noticeable temporary foaming. It's important to note that most parasites in the class that PraziPro® would be used for have up to a 28 day life cycle. This means for major issues, up to four (4), uninterrupted treatments may be required to resolve the issue. Over dosing will not speed impact.
So - I would dose 2x, nine days apart.
Jay