Currently there is no option to set specific times to charge and discharge.
Solar will always supply the home demand first.
There are currently 2 modes, Self Powered and Backup
Backup mode is strictly that, backing up your whole home or circuits you select at time of installation.
Charging in backup mode will charge your PW to 100% using excess solar that the home is not using and power from the grid. Each PW can only charge at 5kwh max so any excess coming from solar will go back to the grid.
Self Powered mode allows you to set a reserve to the PW's percent of discharge. Solar will power the home demand first, if the home demand is above what solar can provide then PW will start to discharge to make up the demand. If the demand is too for Solar and PW then the grid will make up the rest.
Powerwall will discharge to the set reserve then enter "Standby"
Charging in Self Powered mode has a few scenarios
PW state of charge % lower than set reserve %
PW will be charged using solar (if available) and the grid to get to the reserve % as quickly as possible at a 5kwh max. When state of charge meets the set reserve, strictly excess solar will be used to charge till 100%. <- According to Tesla
PW state of charge % higher than set reserve %
PW will discharge if home demand is higher than solar production. If solar production is higher than the home demand, the excess solar will charge the PW till 100%.
So you are able to get the PW to charge and discharge at certain times but you need to play with the reserve to meet your needs. According to Tesla, an update will come out to allow time - of - use or TOU and load shifting to be accomplished, hopefully soon
One thing to note, the PW are capable of discharging at 5kwh continuous. Having your water heater and stove on at the same time will most likely exceed this. I have two PWs so this allows for 10kwh continuous which is better suited for whole home backup / off grid use.
Hope this answers some of the questions