Congratulations on entering the ranks of Title 1. I hope you will come to enjoy it as much as I do. I spent 15 years as a classroom teacher and 10 as a school counselor, but the past 3 as a Title 1 teacher have probably been my favorite. I find that Title 1 allows me to spend most of my time on the parts of teaching I enjoy the most (actually working with kids

and much less time on the parts I enjoy the least (bringing home papers to grade and dealing with classroom management).
Since you already have other Title 1 teachers in your building, hopefully they will be really helpful. Ask them to guide you along. The last year I was a classroom teacher I spent my planning periods shadowing the retiring Title 1 teacher every chance I got. It was extremely beneficial. Even now I will sit in with another Title 1 teacher occasionally just to observe and get ideas for working with individual students.
We always begin our year by getting good assessments / baseline data on our students. Even though students have had DIBELS, SRI and DRA (for K-2) at the end of the previous school year, we begin the year with assessments as well. For 1st graders we do the Observation Survey for those who did not reach benchmarks in kindergarten. With 2nd-5th graders, we often do a DRA for kids who have met the multi-criteria for Title 1 services, in addition to the DIBELS and SRI that are given to all students. I sometimes get too impatient with wanting to jump right in and begin pull-out groups the first week, so my co-teachers need to remind me of the value of doing careful assessment and really understanding each student as a reader. I have to know where they are, the strengths they possess, and areas of greatest concern before I can plan the most effective interventions.
Remember to foster positive relationships with classroom teachers. You need their trust and support. And most importantly, build those positive relationships with students, too. You may miss having a class of kids that are truly your kids, but I think you'll come to love the opportunities to invest in kids one-on-one and in small groups.