Iirc, those ln commands will create the desired links as long as they are executed from within /opt/python/bin. Ln has some syntax quirks that are not exactly intuitive, although they make sense if you think about it. man ln
But I beleive you also need to have the dir containing the executables linked to in your path anyway, security thing. I think your user also needs execute perm in both directories.
Personally, I do prefer the full ln -s /path/to/target /path/to/linkname. Less chance for confusion.