Although fungi, bacteria and specific bacteria taxa, such as the actinomycetes have been studied extensively in various habitats, few studies have examined them simultaneously, especially. The actinomycete colony count in the trifluralin - treated plot was greater than the control, but the same as the..Result obtained showed that fungi populations increased significantly after 20 days of soil incubation. The highest population of fungi was counted after 60 days. The population bacteria decrease continuously during soil incubation while the population of actinomycetes also decreased during soil incubation but it decrease rate was not the same as decreased rate of bacteria. For more details consult https://www.science.gov -- topicpages
It depends on your task. If you estimate populations in plant, soil, or water and use semi-selective medium it will take from 48h to 5 days for bacteria (many gram+ slow growing bacteria) and about 7 days for fungi. If you evaluate biocide effect and use general medium and log-phase culture as inoculum, you can count colonies in shorter time.