In Sun/Moon/Ultra Sun/Ultra Moon, you can find out what a few of your IVs are before leveling, especially with max/min/30 IVs. :P
The Stats Judge tells you if your IV is max (Best/Hyper Trained), min (No Good), 30 (Fantastic), or in a certain range (Decent=1-15, Pretty good=16-25, Very good=26-29).
Characteristics that may show max IVs include: Takes plenty of Siestas (HP), Likes to thrash about (Atk), Capable of taking hits (Def), Mischievous (SpA), Somewhat Vain (SpD), and Alert to Sounds (Spe). :P
From the given information of the stats judge "Very good" and your Characteristic being "impetuous and silly", your Speed IV should be 27. :P