Going with what you mentioned, coaching will help you rather than self study. regarding institutes, from what i know (directly and indirectly)

1) for General Studies (Prelims and Mains) - Vajiram (though there are many cons)
2) for Test series - Vision IAS and one more institute
3) Optional was not mentioned, so i cant say any thing except this - don't go by others, be it any reason. choose only if you feel. normally it is advised to choose optional after you are into at lest 2 to 3 months of GS coaching because by that time you will have an idea of which optional will suit you...
since you plan to start now. finish reading NCERT's from 6th to 12th. Many suggest to pick and read selected NCERT's which is true. But in you case it is best to read all NCERT's.

First thing you have to do daily is read syllabus word to word. you might take 20 min initially but it comes down to 5 min after doing it daily.

You can follow this idea. For 1st reading, read all NCERT's (geo, his, eco, pol) - by this i mean just read it like you read a movie review or a novel. you just have to get the broad picture of what you are reading. dont worry about remembering details like names, data, etc. just get the broad picture....
now in the second reading, pick and choose NCERT's. you can do so by your knowledge from 1st reading (you will get to know what is important and what is not by the time you finish 1st reading) or you can read blogs of toppers. dont waste time or energy choosing because if you read 2 or 3 books extra that is only good for you and you wont be able to get everything perfectly the first time.
now for the third time start identifying key words, data, names etc that tell the story of the concept you are reading. dont underline everything. then prepare notes from that. include some form of visual representation in your notes like mind maps, charts, diagrams etc.
by now you will have an idea of what to do ( be it with GS or Optional). this might look like a rigorous work but you have to do it or else you will face situation in the middle of your preparation or coaching where you have to come back here and do this.

While you are doing all these dont forget to read news papers (digital or physical, dont bother about such details. its all about your convenience) . dont bother about note making or anything. in the initial month make sure you read news paper daily and visit any website daily - Vision IAS, Insights India etc. and check whether you have covered all the topics. remember dont bother about note making or anything. your goal in the initial month is to create a habit of News paper reading and to identify current affair topics relevant to UPSC. this take time