How do you plan future projects?

Since it's impossible for the client to upload files to a project that are already planned (even though it's not started), how do you plan future projects? Let's say you know a client are going to send you a text for translation on a specific date. The best thing to do is of course to create the project, send out the request and plan everything in advance. But then the client cannot use the client portal to upload the files, since the project is already created. Then we're back to the emails again.