Stop all this silly stuff, it's time to use our powers properly!
At any point, one normally has two or three forces acting upon oneself - gravity pulling us down, the bouyancy of the medium (usually air or water) pushing us up, and (if standing on a surface) the suport of a surface to prevent ourselves going through this.
now let us remember that momentum is equal to force, or:
mv=Ft
in the above equation, it it t that we control, that we have a mastery of.
Each of there three forces will combine to form our overall momentum, so our motion will be governed by the equation:
mv=t(FB-FG+FS)
Where FB is the force of bouyancy, FG is the force of gravity, and FS is the support of the surface we're on.
However, we should now note that FS is not always present. Instead, it is only present when we would otherwise fall through a surface, or when:
FG>FB
however, this is not often the case - indeed, this only naturally occurs when we are in a very dense medium, so the mass that is displaced is greater than our own. Normally we would be constrained by that, but instead we are a wizard, not limited by such petty things! Furthermore, we are a mighty time wizard! We are bending the very laws of reality, and the one that shall be bent here is the rule that t must be constant. Instead, we can denote the times as such:
mv=FBt1-FGt2+FSt3
Now, using some wizardy maths, let us look at the situation where FBt1>FGt2. FS would not exist, so we get:
mv=FBt1-FGt2
mv>=0
FBt1-FGt2>=0
FBt1>=FGt2
t1/t2>=FG/FB
Let us now denote the time factor T as t1/t2:
T>=FG/FB
So, to summarize: using our time magic, we increase the rate at which the bouyancy force of the medium (air or water or whatever we're in) acts upon us. If we want to simply levitate, we increase it by a factor of T, whereas if we want to accelerate upwards, we increase is by a factor larger than T.
>Put this theory into practice.