Why does for loop skips the first i++

Explanation

Since it is 0 at the beggining and it runs through i++ once before it executes shouldn't i start with 1?

That is incorrect. The last part of the loop header, i.e. the C in for (A; B; C) is executed after the iteration, not before.

Execution order

So if we unroll the loop, it executes like this:

int i;
i = 0
if (i < 5) {
    System.out.println("i = " + i);
    i++;
    if (i < 5) {
        System.out.println("i = " + i);
        i++;
        ... // until the condition is false
    }
}

Hence why the first iteration has i = 0 and not i = 1.

for to while

An alternative way to express it is by using a while loop. Basically

A;
for (B; C; D) {
    E;
}
F;

is the same as

A;
B;
while (C) {
    E;
    D;
}
F;

Note how it is first E and then D, not the other way around.

So in your case we have

int i;
i = 0;
while (i < 5) {
    System.out.println("i = " + i);
    i++;
}