A downhole tool for use in completing a well includes a plug body selectively securable to a wellbore at a desired elevation and having a flowbore. A non-dissolvable flow restrictor is operably disposed in the flowbore and operates to restrict fluid flow through the flowbore, and a time-dissolvable retainer or spacer is operably coupled to the flow restrictor to retain the flow restrictor in a first position within the flowbore. The retainer is dissolvable within a predetermined passage of time to release the flow restrictor to move between the first position and a second position within the flowbore to control the flow of fluid through the downhole tool.