It looks good ,but you could just reduce 64 to 10 for dayName, and 30 for dayMonth and monthYear so you could optimize the storage (remember this is an ESP wich is not a very powerful chip so optimizing the memory usage is necessary),and also you could add a log statement to keep you informed for example ESP_LOGI(TAG, "DST: %s", DST ? "true" : "false");.