How long does it take your bf to grief after mothers funeral?

My boyfriend's mom just recently passed away from cancer. They had the funeral Monday June 20. How long does it take him to grief? I haven't seen him in like about two weeks. He was taking care of his mom with lung cancer and his kids was helping him. So how long should I go without seeing him? He always came to see me. And I know he has been through hard time. But it is like I am wanting to see him so bad. His kids are grown and he is grown but I don't know how long this would take. It is like I want to see him so bad and wanted to be around him to help him out.