u/Otherwise-Degree4049

Hello,
I’m running my first marathon (CIM in December)- 25F. I have been running consistently for almost 3 years now, and have recently run my first half marathon in 1:50:53. I want to set a goal of sub 4 hours, with a decent training plan, is this realistic? Or should I aim for 4:05-4:10? Also any recommendations on training plans as this is my first one? Thank you!!!