Career advice: How can I move on from my probable PhD flop?
I am going to answer from a rather different perspective, that of someone who has been involved in technical hiring, the sort of person who is going to be looking at your job application and possibly interviewing you if you go into industry. I'm a retired computer programmer and computer architect, and have spent many hours trying to pick the right people to hire.

I had a colleague who started on a PhD. and decided after a few months that he was not suited to that path, and would do better in industry. That was absolutely no problem.

On the other hand, quitting at this point, or later, in a 4 year project is a potential red flag. It would make me worry that you may throw up your hands and quit a few months before a deadline if the going gets tough, rather than rising to the challenge. That would be a serious negative for most technical jobs. Moreover, even if you think you know what went wrong, why you did not complete the PhD., you would have nothing to show that would give me confidence in your analysis.

On the other hand, suppose you continue with the PhD. through September, putting together the best thesis you can in that time. If it is accepted, great, carry on with the academic path. 

If it is rejected, you still have something to show a potential employer. You would need to analyze what went wrong, and understand your strengths and weaknesses. You either need to correct weak areas, or pick a job that plays to your strengths and does not need your weak areas. For example, if your thesis has insufficient original results but is well written and presented, you could apply for jobs where original research is not required, but organizing and presenting technical information is important. There are plenty of those.

In a comment on another answer, you say "my supervisor has had a lot of successful PhD candidates". That means he is both good at picking students, and good at shepherding them through the thesis process.

I think the time to start looking for industry jobs is after the very best thesis you can write by the deadline, taking full advantage of your supervisor's advice and shepherding skills, has been rejected.