Effexor (Venafalaxine)

I was diagnosed with General Anxiety Disorder about 12 years ago and was put on Effexor. 2 years ago I had a lengthy episode to the point it was necessary to increase my Effexor dosage to 375 mg daily. I’ve been relatively stable since then and now trying to reduce my dosage. I am scared to reduce the dosage because of how bad I felt 2 years ago. I have worked hard at giving myself different tools to use (DBT, Music therapy, meditation, breathing techniques)
I don’t have a lot of medical support as the Psychiatrist that worked with me for almost a year passed away and there was nobody to replace her. I live in a very small rural community. The locum for my town told me to try reducing from the 375 mg to 300 mg daily. I’m on Day #4 and so far so good. I am wondering if I am going to experience negative symptoms, how long it might be before that happens? Thank you