how many syllabus should be complete till december for neet 2022 in pcb to get 670+ ???????

By December end, your AIM should be covering atleast 75-80% NEET Syllabus strongly, if not 100%. Whichever topics youre weak on or need some guidance or practice, can be worked on in the remaining months, besides regular revision of Completed Syllabus. You should take a Good Test Series like Allen and Aakash besides appearing for regular/weekly tests and analysing the Papers. For securing anywhere above 650 in NEET, not only do you need a proper preparation strategy, but equally important are strategic selection of preparation material and test taking strategy.