It would be much more effective for you to get into the habit of practising at least a little bit every day. If you practise for just one or two hours every weekend, your progress will be much slower.
Of course, if you have one or two hours of Italian practice with a teacher on Italki every weekend and also do some daily practice on your own/with a language partner, then this could be good, But if you only practise for one/two hours every weekend and do no other practice for the rest of the week, then your progress will be considerably slower and less satisfying.
I think it is also a good idea to focus on only language at a time (ie choose either Portuguese or Italian) to avoid confusion between them/dividing your time between them.
If you already know some Portuguese (and English) you will find plenty of words that are similar. However, this doesn't change the fact you will need to practise regularly to improve.
If you find a good Italian teacher and follow this advice/the advice of your teacher etc, you'll make good progress.