Just over halfway depending which faction you side with. Things start to move fairly fast from that point on, well from as soon as you get inside the Institute. If you want to do side missions or grind your XP, as well to take a step back from the main plot now to focus on that.
Main story related:
For me getting to institute finished the story. I knew he was safe and doing well for himself. Not sure I will continue any further. I have no interest to side with any of the factions against others. I'll probably just keep exploring ,building my settlements and ignore rest of the main story line.