I would house a frog that small in a separate tank about 5-10 gallons in size with the appropriate accommodations, for a temporary time. Also, any new frog you get should be quarantined in a separate tank for a month or longer, before being added in with other frogs. New frogs can have diseases/illnesses that don’t show up until a later time.

A baby WTF can grow up to 0.5 in 3 weeks; at that rate the frog could grow 1.5 inches in 2 1/4 months. However, depending on what you feed the frog and how much, will affect the growth rate of your frog. So it could take quicker or longer for the frog to reach that size.