Modelling D&A if not given

% of sales dude. don’t overkill yourself. or get it from CFS. cleanest source

put together a depreciation waterfall and project capex

I'm not in PE but the CIMs I receive are typically just a Pro-Forma P&L and working capital schedule (if I'm lucky). I typically just ask the banker what the historical CAPEX and D&A has been, then verify in confirmatory diligence.

Curious to see how others go about it.

Have it equal capex. That's a pretty conservative approach and you don't really want to be underwriting returns based on D&A or the tax shield you get from it exceeding capex.