You joined this forum as far back as May 2015, and you've been posting since then. Claiming English is not your first language as the reason why you can't look through a simple spreadsheet to find the information that you need doesn't come across as a legitimate reason IMO. BUT I will give you the benefit of the doubt this one time:
Your question: "If i decide NOT to fill the DS-260 [since its optional for AOS], can i still get the 2NL from KCC."
Applicable Answer form the AOS_FAQs tab of the AOS spreadsheet:
DS260 form submission is what typically triggers the AOS based 2NL (DS260 form informs KCC of your plan to process AOS, KCC responds by sending an email (with DV administrative fee payment instructions attached) acknowledging their awareness of your AOS process decision).
If you choose to not submit the DS260 form, you may still get an email acknowledging KCC's awareness of your plan to process AOS after you've made the DV administrative fee payment - this is your 2NL. If you end up not getting the 2NL (after making the DV Administrative fee payment, don't stress over its absence.
Your question: "What is the best time to submit the DS-260, in order to get the 2NL KCC letter on time. [ do i need to wait for this before i send the package]"
Applicable Answer form the AOS_FAQs tab of the AOS spreadsheet:
You can submit whenever you like. KCC does not process the DS260 forms for AOSers like they do for CP. However the sooner you do, the sonner you will get your 2NL
Applicable Answer form the AOS_FAQs tab of the AOS spreadsheet:
Yes you can submit the AOS package without the 2NL.
See? Answer to most of the basic questions have already been covered on the AOS process spreadsheet. You just need to carefully go through all the different tabs of the spreadsheet if you've never done so before. You may need to do this a couple of times to familiarize yourself with the different steps and listed information.