JMO you're going to be outbid bigtime and you won't get any work with the above fees. For general notary work (which you should be doing before any loan signings - be an outstanding notary before trying to be a great NSA) you can charge the $15/signature plus mileage and time but I find it hard to believe that you'd get the fees this schedule would generate doing loan signings..example - loan signing with 8 notarizations, married couple, so 16 signatures:
25 miles total (if you lucky) - $14.50
16 signatures - $240.00
Paper/supplies, etc - can't even put a price on this
Courier Services - $100.00
Based on your outline you've priced a loan signing at $354.50+ - I just don't see that happening.
Also, don't forget to include Federal and State Income Tax in your calculation of your fees. Your income is subject to federal income tax - the only exemption is the fees you can charge for notarization (for you, $15/signature) is exempt from Self-Employment tax only. I don't know how your state income tax is structured so I won't comment on that.
Don't forget the other little items - advertising, business cards, listings, certifications, commissions, etc etc - PER HOUR OF YOUR TIME - time is money and your time and expertise have a value.
To answer your question, when I did loan signings, 30 days was my net due date...unless I agreed to 45 prior to signing. I would not agree to 60...so I'd say 30-45 days (days, not business days) is acceptable.