My plan is changing 20% of water in this basis :
3 day --> 7 day --> 14 day --> 17 day --> 21 day
If you have any other solution for that going to be great to have it.
I don't understand the writing on the bottles you've shown, but assuming that one consists of nitrifying bacteria, the general way that works is by adding fish, bacteria; which over the course of two weeks builds up your bacteria colony and keeps the ammonia at a non toxic level.
Conversely, if you are cycling with pure ammonia, you would add small levels daily over the course of weeks; until you start to read nitrites, this then goes on until you read nitrates, thus being fully cycled.
If you simply add your oscar, then do water changes; there is a very high risk of killing the fish, as the ammonia will skyrocket; which fish can't handle.
I'll try and find the link for cycling fishtanks for you, also you might want to google "tetra safestart" if you are interested in the bottled bacteria option. It has mixed reception on this site, I use it for all my tanks however.