Welcome to Phase 2.
Congratulations on completing Phase 1. You are you on your way to greatness!
Once the first phase is completed, the focus now is on getting the next level of IT certifications within a year. You need to press on at this point, and stay extremely focus to keep the momentum going. My estimation is that this part can take most of us about a year, but it's possible to get it done in less than that time frame. It's going to depend on prior experience and other factors.
This is a very important phase. It's going to require more intensity now that you've completed the formal education requirements and have an administrator level job. It's not the time to relax or slow down as this period requires a greater technical depth to master the subject matter for these higher level certifications.
The certifications that I recommend are: CCNP Security and/or the CISSP. CCNP Security is a professional level vendor specific certification from Cisco and is well respected in the industry. The second one, CISSP, is especially useful if you intend to get into IT security management. You will not regret spending the time preparing for the CISSP as it will instantly raise your profile and give you bragging rights among your peers. These exams will absolutely pay off in terms of earning potential and professional advancement.