Thank you for your answers!

Regarding traffic, I'll say that we don't live in Moscow, so you can divide everything by three. There is traffic in the center and on the ring road during peak hours: 8-10 am, and from 5-7 pm. But since the 30th is a Saturday, everything should be more or less free!

I'm not worried about St. Petersburg, as it's Saturday, but I am a bit worried about the road to the suburbs (towards Avrora).

Real Heroes always take detours! Maybe we shouldn't even enter the city?

We'll be coming from the opposite direction (from the southeast), and we need to go to the northwest. Or are you suggesting driving along the КАД (Moscow Ring Road) to Kronstadt and then exiting towards Sestroretsk? I don't know the roads in St. Petersburg, and I wrote the route based purely on the map.