I am always getting Bacillus during isolation of actinomycetes. It is grow in 12-24 hours. So all the plates are covered with Bacillus then actinomycetes start to grow over.
You could use novobiocin (10 ug/ml) to avoid Bacillus contamination.
Other possibility is the use of different isolation media, which could enhance the chance to isolate actinomycetes, such as: SM3 (Amycolatopsis and related genera), SCA (streptomycetes and related genera) and HVA (many genera), etc.