If the plaster is getting loose (which may happen due to decrease in swelling at the site of injury), you should revisit your doctor and get the plaster re applied.. If swelling has completely gone away, you may go for full plaster application (cast) so that it fits properly in the upper limb.. Healing period for fracture is usually around 6 weeks..
Next Steps
You may continue active finger movements, avoid placing limb at a lower level..