When to bring in a GC for estimate

[Christopher Canning]

Newb question: I'm planning on doing the BRRRR strategy, and I've been looking at a number of SFH in my area. I feel like I've got the point where, if I see something pop up on the MLS I know immediately if it will be a good candidate or not. However I still do not have the knowledge that I feel like I could use to know how much the rehab will cost.

Most of the houses that fit my requirements that end up on the MLS in my area are foreclosures. My question is; if I know the deal looks good before I even look at it, should I (1) bring in a GC on my first visit to a property to get a rough rehab estimate before I put in an offer, or (2) should I put in an offer using my guess of what the rehab might cost (based on my little to no experience), then once under contract, get it inspected then bring in a GC for a quote on my SOW and then attempt to renegotiate?