Not all plants that have pollen have nectar, at my home base I just lift my hive to see if they are putting one weight, that can tell me if the honey flow is on. I know approximately when our honey flow will start and finishHow can you tell if it is a heavy flow or light flow? Does a plant that has a good looking pollen bloom mean that plant will have a good nectar flow?
it will change slightly from year to year. This year it was extended by about 2 weeks because of the wet conditions. Its important to monitor your local conditions.
In my out yards I have set up broodminder which I monitor remotely via cel, one scale per yard and temp monitors in all colonies.
I can tell exactly when the honey flow is on. right now my out yards are in dearth. Today the data shows me that for the last 2 weeks they have been consuming slightly more than they have bringing in. The fall honey flow should start about end september here in Texas