No one else can tell you what is the best way to operate your wash. I'm guessing that you have not owned/operated this wash for very long. If that's the case, it can be an expensive learning curve because you don't have a revenue history to know your potential business.
I used to operate 24/7 with my underfloor heat "On" most of the winter. For the last several years, I only open the wash when the temperature is above freezing and I expect to do some business. I may open only 1 or 2 bays. When it looks like we might actually do something, I turn the heat "On" about 2 or 3am and make sure the bays are all de-iced (I use hot water from a hose hooked up in the equipment room). Some days you mis-guess and lose your a$$. I have spent over $100 in natural gas and only done $60 worth of business.
I personally don't worry too much about customers finding other locations or developing new habit patterns. Hey, if there were customers looking for a place to wash, I'd be open. Around here, people just aren't washing their cars that much anymore. I see it at every wash, and have heard it from other operators. In the town I live in (not the same as where my wash is located), there is probably enough total business to support about 8 bays; we have about 34 bays spread between 6 washes.