Alkalinity and calcium hardness do not burn off like chlorine. With a SWCG however, you're always fighting a rising pH. To combat the rising pH, muriatic acid is used to drop the pH which also drops your alkalinity.

A key factor is what level of alkalinity (TA) and calcium (CH) you have in your fill water and how often you need to top off your pool.

In my own case, both TA and CH were quite low in my fill water (50 TA and about 70 CH) so I needed a good amount of baking soda to raise my TA and I used calcium hypochlorite to chlorinate my water (and to raise my CH) for about 2 months until my SWCG came online.

If you know what your starting TA and CH numbers were, I'm sure the guys and gals who service pools can give you a good idea of how much is "normal" in starting up a pool.