You need to memorize it. You can't put a time limit on a language, it comes down to how much time you have and no matter what it will takes months at a minimum for basic conversation.

It may have been easier for me, as I am Italian, so I'm used to conjugating verbs. But really, you just need to study the conjugation, if you take it seriously it won't take you more than a few days. Just take five minutes every now and then and repeat to yourself the conjugation of a tense (check with the reference so that you don't learn it wrong!). It's not hard once you get the hang of it, and then endings are mostly shared between the diverse tenses :-)