wordpress index.php没有显示出来

I want to re-do a website using Wordpress. Since I don't feel confident in developing it somewhere else then moving it to the server once completed, I've moved the actual website on a subdir, put a index.html file containing just a redirect on the root, then installed wordpress.

Plan is: visitors just calling the url will get index.html, so will be redirected to the old website in the subdir, while I should be able to call url+index.php to check the wp website in development (since html has priority over php).

Once website will be completed, I'll remove the index.html file performing the redirect and visitors should start viewing the new website.

Problem is: even when calling url/index.php I'm redirected as if I had not added the specific request to index.php file.

Any help?