Should I get estimates from contractors during my first walkthrough or second?

[Nicholas Saville]

I'm trying to purchase my first investment property and I'm doing it step by step for I am new and it's easy to get lost in the process. So I'm in talks with a lender to get pre-approved and already have an agent who's been extremely helpful in providing spreadsheets of contacts for any specialists I'll need during the real estate investing process. I found a house that I'm interested in and my agent has gotten me a list from the city inspectors as to what needs to be fixed/replaced (obviously I'll need to do wayyyyy more renovation than what's on the list, but it's a good start without ever being at the house so far). 

So my question is... when running an analysis, should I get multiple estimates from general contractors during my first walk-through of the property or get estimates on my second walk-through? I don't want to put a lot of time into scheduling the estimates if there's a big red flag with the house (money pit). 

I'm new to real estate investing and work a full-time job. So I'm not available 100% of the time for scheduling and viewing properties. I'm trying to go about this with a cautious conservative approach while also understanding the importance of being quick to grab a good deal, but my scheduling is currently a mess.

Thank you for your feedback