Blogs have been watching Sims's Web site closely, and on Monday Spears's former assistant updated it to include her first song – a cover of "On My Own," from the stage musical Les Misérables.
And, the newly launched singer tells PEOPLE, she already has a staunch supporter in Spears.
Shrugging off rumors that Britney resented her decision to pursue her lifelong dream, Sims, 26, says: "She heard my songs on the laptop and was like, 'I love this song! This is you singing?' She has always been supportive."
As for Spears's parenting skills, which have come under fire recently, Sims tells PEOPLE in its new issue, "She's a wonderful mom and she is so hands-on. ... Britney loves those babies to death. And they adore her."
When it comes to her former employer, Sims adds, "I love her, she's beautiful inside and out. We're still great friends."
And when it comes to her music, the Southerner says she's after a "soulful" sound, and the single on her Web site is "more of a filler song until I get my new stuff recorded. Honestly, we put that one up there because all the other ones I had put down in the past had a little more of a country vibe, and I do not want to go there at all."
Further distinguishing herself from her famous friend, Sims also says, "I don't dance, I'm not pop. I have a more bluesy voice, more Norah Jones-ish. I don't want to appeal to just my age group and younger."
Having moved to Los Angeles immediately after college with a music career in mind, Sims made ends meet by working with noted wedding planner Mindy Weiss and, more recently, for Spears.
"I was just doing that for a little while, and we had a great time together," Sims says of working with Britney.
Now, however, Sims is making music with the likes of such in-demand producers as Evan Bogart and J.R. Rotem.
"I hope everything falls into place, and maybe by January I will have a lot of things under my belt and get to release something," Sims says. "I just want to do what I love. [Music] is my passion."