Although your E-Liquid is perfectly fine and ready to use straight from the bottle, Steeping will greatly enhance the flavour.
Essentially steeping is a process, or number of processes, used to blend, age and mature an E-Liquid, to the point where the best flavour can be obtained from vaping it.
Steeping will provide the best possible flavour from your E-Liquid by rounding out any harsh flavours, blending multiple flavours together, developing, maturing or ageing flavours.
Flavourings need to completely diffuse into the types of base liquids that are used, these need time to bond molecularly with any single or combination of base liquids used in a mix (Nic base, PG, VG, etc). In addition, air is required to interact with the liquid, this causes oxidation, replenishing the air in the bottle will help oxidation and in turn quicken steeping, leaving the cap off helps (but make sure it is in a safe position).
As a liquid steeps it will normally darken, this can be an indication to when a liquid has matured (molecular interaction with nicotine causes this - We have noticed the higher nicotine content, the quicker a juice will mature and the darker the liquid will become).
The most traditional method of steeping is “Time”. Leaving the top off the bottle (allowing air to get to it) will steep and improve an E-Liquid by itself, this is usually done by placing the opened bottle in a cool, dark place for anything from a day or two up to a week or more, occasionally giving the bottle a swirl to replenish it with fresh air.