I have been teaching programming for close to 35 years and I assure you that there is no particular order in which you have to learn programming languages. Each programming language is independent so follow your syllabus or your need and you should be good.
However, if you want to create a more optimized schedule to learn faster, I suggest you do C and C++ together. You will find many similarities in these languages. After a point you can start with OOPs in C++. By this time you will feel very comfortable and will be able to learn plenty of Java on your own. The syntax of C, C++ and Java is very similar, many keywords are common, and a program written in one of these languages will work just as well in another with small changes. So for example, C has its printf() statement, C++ has cout() and Java boasts of system.out.println() but not very different or difficult to understand.
Once you have completed the basics of synatx, looping statements (for, while..), decision making statements (if, switch..), the various operators (mathematical, bitwise, logical), you will find that you have to study pointers, structures and unions in C, while C++ and Java move on to the domain of object-oriented programming (OOPs). Other common concepts will be file handling, algorithms of searching, sorting, data structures like linked list, stack, queue will be common to all these languages.
You may also start with Python although you may find the syntax of C, C++ and Java a bit challenging if you go from Python to these languages. Use of libraries in Python will be a new feature.
Once you have studied C and / or C++ you will find that the other languages from the set [C, C++, Java, Python] are relatively easier to pickup, with just a good book beside you. Infact, even Visual Basic for Applications (VBA) for Excel and other Microsoft Office products becomes easy to learn. A few good books are recommended here.
So, in my opinion, the sequence is (C and C++) —–> Java ——-> Python. In fact I take online courses where I follow this sequence and find students do it very well.
Do share your opinion about what order of learning languages is more helpful.