I’m not sure why your system boot is affected, because your user bashrc shouldn’t be involved until you log in. It’s a little hard to guess exactly what’s going wrong without more diagnostics, but I think @vgaetera has the right suggestion — there are tools better suited for this job. In fact, it’s literally what systemd is made to do.
I haven’t tried it myself, but here’s a systemd config someone made which should at least get you on the right track: