You'll know when you no longer have to ask this question.
It's one thing to put ketchup on a hamburger and onto french fries but to put it on top of ice cream and into soda? That's just disgusting!
It depends on what you want to express.Rubato cannot be discussed in general, every single situation (even the playing of only 2 or 3 notes) has to be decided carefully.There's no switch like rubato on / rubato off.
Romantic music (the style) and especially Chopin are known for the extensive use of rubato (however, Alkan didn't like it at all and suggested that even Chopin should be played the classical way but he was quite alone with that at his time and even today). Well, rubato is an extra tool for expression and the best way, to learn when to use rubato is to try it out. Humming alone can help a lot, our voice is the most expressive musical instrument on earth and it has a lot of automatic "features".
I have to disagree with the statement that the music of Chopin is romantic with extensive use of rubato based on Chopin's own statements and those of his pupils. Chopin was appalled that some of his students and other pianists played his works in such an abhorrent manner. He condemned this fancy-of-the-times, among others, that was so prevalent by certain pianists (e.g. Liszt) - etc. etc. etc.
Even if we were to continue to label Chopin's music as romantic, this does not justify the use of unnecessary rubato.