Yesterday, I passed the AWS Dev- Associate level certification. I had spent 3 months to pass CSA. So that helped a lot. After passing CSA, it took just one month to prepare for Dev cert as there is overlap between Dev Cert and CSA. CSA covers a lot more grounds, Dev cert goes a bit deeper on selected developer topics. Apart from following the instructions twice or thrice, I also reviewed the "Further Reading" material suggested in the practice quiz answers. The practice quiz definitely helps.