For the time taken, it heavily depends on your method. For example, obtaining protein by acetone precipitation usually takes me ~9 to 10 hours, but using Filter Aided Sample Preparation (FASP), I only need around 5 hours. However, in any case, trypsin digestion of your proteins will take ~10 to 12 hours, and an extra 1-2 hours is needed for desalting the peptides (I use ZipTip/SpinTip). This also depends on how much samples you have. All the time listed here doesn’t include LC/MS-MS injection time.

For proteins needed, I usually took 50 μg if I use acetone precipitation, or 200 μg if I use FASP. Cells needed will vary depending on your species analyzed. For bacteria like E. coli, 108 cells is probably enough.

You can find the protocol for proteomics experiments in proteomic journals such as Journal of proteome research, Molecular & Cellular Proteomics, etc.