Great welcome to the world of speedcubing!
That was the method that I originally started with as well. I believe that you should try to get your times maybe a little faster than that before trying to learn F2L. Perhaps 1:15-1:30 range. The more time you spend with your cube the better you are going to get. The more solves you do, the more you will start to notice patterns and make intuitive adjustments throughout your solves. Also I recommend learning other ways to insert corners when solving the first layer other than R' D' R D, such as (depending on the situation) L D L' D'. One tip is to learn to transition between steps as fast as possible. Like as soon as you finish your cross, immediately start corners with no delay, as soon as you are done with the 1st layer, immediately begin to insert edges, when done with edges immediately begin top cross, etc...
Good luck!
