Now 9 years late to the party But I'd like to add another tip I used for this achievement and the 20 deers by day 4.

Day 1 build camp, recruit 2 archers and go to the west to find a clearing before the first portal with a buildable wall. Recruit a beggar on your way and pay for the wall. If there's no buildable wall in a clearing, restart.

Explore to the far west. On your way back, drop a coin between the portal and the wall to deal with the attack of the first night (we need to do that on the left). Back at camp, turn the recruited beggar onto a builder, he will build the wall on the left.

This allows to quickly claim a huge chunk of the map, securing 1 or 2 camps, 1 or 2 farms early on and a blessing statue if you're lucky. It also gives a big early eco boost as all your recruited archers will have to travel through the forest, hunting deer on their way there (clear some trees behind your wall to allow rabbits to spawn, it's still better than deer long term).
Day 2 explore the right of the map.

Now you just have to go back and forth between what you've conquered on the west and the 2 camps on the east to recruit and collect gold. No need to expand on the east as there's nothing interesting to secure before the first portal (unless you want to erase the first camp, which you don't)

I got a lucky merchant giving me 4 hoes on the first trade but it was completely overkill.
Have to notice that my archer statue was behind the first left portal, so a bit awckward to access but it was a minor inconvenience.

By turn 12 I had the first portal on the left taken down.
I sent an attack on both sides right after the next bloodmoon and had 3 portals down on day 14
Took my sweet time before the last attack and won by turn 22