Usability Heuristics - Interaction
The system should always show the status of an on-going operation to the users until it is done. So the user will get a clear understanding of the progress of that particular process/activity. Never create a situation where the user is completely confused over certain progress/process.
In this design, the progress bar on top doing the job by indicating 3 out of 5 images are uploaded. Here the user is well aware of the progress and can wait without any hesitation until the process completed.
Read my article on medium about Heuristic Evaluation and its methodologies