Can a beginner get rating of 1500 in 3 months ?

The jump from your current rating (820) to 1500 is a big one. Getting to 1500 for the first time is not that easy of a journey, I think with an extreme amount of hard work done correctly you could get close, a little unsure, but if I were I would aim for 1000-1200 as it's a much more realistic goal that doesn't require a crazy amount of work.
https://www.chess.com/blog/KingsideCastleNotation/how-i-got-2000-a-guide-for-you
I also made a blog, it says it's a guide on how to hit 2000, though the information is pretty universal to players of most skill levels.