Disclaimer: I am not a lawyer and my suggestions should not be taken as a legal advice.

Changing from OPT to J1 should be the last resort. There may be few technical and legal considerations. If you must do it, make sure before application that you will not be subject to two years 'Home Country Residence' as part of J1 approval. Talk with a good immigration lawyer before you do anything. It may be that the other person will also end up doing nothing between May and October.

You shouldn't apply for J1 after you apply for H1B. Generally, the second application prevails over the first one. There is a high chance that immigration officer will reject your H1B application if you submit J1 visa application after H1B application.