You definitely can do it. But it does depend on your goals--progress will be slower if you are dividing your focus but that is okay. It's definitely easier to start learning another language once the first language is conversational. This is especially true because Polish and English are quite different since they are in different language families. For practising both languages, one thing you can do is write your notes for Polish in English (supplement with Russian if you need to). Think about how much effort you want to put into Polish at first relative to English. Starting a new language requires more focus than one you are more familiar with. Pick a schedule that you think will work for you, try it out for a week or two, then reflect--is this working? Do you need to change anything? Lindie Bootes on Youtube has a video about this too. For English, if you are at the stage where you can read okay, you could try for more passive exposure throughout your day by changing the language on something you regularly look at (e.g. I have most of my social media accounts and my phone set to target languages). This can be a bit of a learning curve at first but I have found it quite helpful. This would allow you to at least have some exposure to English on days that you are focusing on Polish. I'll add more if I think of anything else, but I hope this helps :)