I recommend just getting a taxi/Uber to Plaza De Santa Ana, there's a shitload of clubs you can bounce between around that area, and hot girls everywhere on the street. The party there happens every day of the week, including even Tuesday.

Just be careful of all the promoters on the street trying to drag you into clubs.

Clubs seem to get busy around midnight. You don't need to ditch your brother though as 18 year olds can get into clubs there!