Any tips for bonus level 12?

Can't seem to finish in three star time. Would appreciate tips!

I had to play many times for this one, and timing is so important.
I used the freeze bonus exclusively.
I also changed back and forth between the cloak (wood) bonus and stone bonus.
Remember to work towards building units all over, this was the order I did it.

Build and upgrade Food (I hate calling it the other name)
Build and upgrade Wood
Build Forge
Build Quarry
start collecting solar panels (3 X.s)
Upgrade Quarry
start collecting gunpowder (8'Xs)
Build and upgrade Iron
Start collecting springs (4'Xs)
Upgrade Forge
Use Upgrade all bldgs. bonus
Clear to sand and collect 3
Repair Lanterns, 2
clean up acid
repair power station
repair chiefs house
take sleep aid from chief and give to snake
Make magnify glass (maybe before you need it if you can) and use it

Hope this helps.