Finally tackling the backyard deck rebuild

After 2 years of looking at this rotting mess I'm actually doing it. Pulled off the old boards this morning and the substructure is toast. Gonna need all new joists which means this is way bigger than I thought. Already spent $400 on lumber and I'm only halfway done planning. Anyone else start a project thinking it'd be a weekend thing and suddenly realize you're in for months of work? Tips appreciated.