Contractor payment structure?

[Yacine A.]

We have a fairly large remodeling/home expansion project in Bay Area (northern california). It involves a garage conversion, building a new single car garage, and adding 600 sq ft to the living room. So in total we are adding 900sq ft of living space including converted garage and the living room expansion. Additionally we are remodeling most of the house and adding a new bedroom and bathroom, entire house will be 2100 sq ft afterwards.

We received 5 detailed bids. We chose two to pursue. One is total of 400K and other is 330K (the difference is actually 60K given the bigger quote includes some finish material as well, but most of finish material is on us). We are choosing the more expensive quote because they are more experienced in larger jobs and are based close by.

The timeline given to us originally was 4-6mo across 3 of the contractors including these two. Now at the time of signing, our chosen one is increasing to "max of 6-7mo" and wants to put contract expiry at 8-12 months. We are worried the project will drag on.

This is the payment structure. Do you think it is front loaded too much? Anything else about the timeline seems strange to you? The cheaper option is still on the table and has <20months timeline.

14.25% prior to start ($57,000)
13.25% upon foundation inspection ($53,000)
15.30% upon framing inspection ($61,200)
5.20% upon plumbing inspection ($20,800)
9.75% upon electrical inspection ($39,000)
5.25% upon water proofing, drywall and insulation ($21,000)

7.25% upon roof inspection ($29,000)
8.0% upon stucco ($32,000)
9.25% upon flooring kitchen and bathrooms ($37,000)
12.5% upon final inspection and finish final touch ups ($50,000)