and how much should i steep it to do a fair judge over it because these steeping process is very confusing for me.
I think I responded to another thread of yours and if so, I may be repeating myself some.
While we all have different taste sensitivities, unless you are SUPER sensitive I feel that you may have gone too far the other way with TFA flavors. Smooth and Ethyl Maltol are basically enhancers moreso than a real flavor, so 5.5% of actual flavoring using TFA seems very low to me. That said, some people like it that low so it's not inherently wrong, but it's quite common to see *total* flavorings approaching 15-20%, especially with TFA. Some other flavorings are more potent but I wouldn't bat an eye at 12-20% TFA, personally. Many of my juices using most or all TFA are in that range, especially fruits.
Steep time depends on a variety of factors: the flavorings and brands used, personal preference, how much usable liquid you already have, and simply how long you're willing to wait. As a general rule, juices made with only fruit flavorings need the least amount of time and can often be vaped immediately. A couple of days steeping is usually sufficient. Fruit and cream, fruit and bakery, and cream/bakery/dessert vapes need a little longer... 5 days to a week, again somewhat depending on what exactly is in it. Tobacco juices need the longest, say 10 days +/-.
The above is just what works for me, and as far as I know is probably a good general guideline. But someone could also come on here and say "I steep all of my fruit vapes for two weeks and they're awesome." DIY juice is, by definition, a very personal endeavor if you're not selling or giving it to others. Some problems will have to be solved by trial and error. While we can and are happy to guide you, not every answer that comes from strangers on the Internet is always going to work for your purposes.