Hey Ridgeview!
I like to take two proficient spear dwarves as my starting dwarves and let them start training right after the first few buildings are set up, so maybe 15 minutes into the game.
I also like to minimize my starting equipment by taking bituminous coal and malachite with me and smelt/forge all tools and armour I need in place. I also take about 60 rock blocks with me to immediately build a small fort around my wagon with a 1-tile entrance and a bridge as roofing. Once my smith has axe, pick and spears ready he's set to make mechanisms and my carpenter makes a few wooden balls. This way I have a defendable position with a trapped entrance within 25 minutes at the latest.
When I started my last fort in the tropics the region was housed by a human pikeman that took shelter in a leather tent. Since I was at war with humans he immediately ran for my embark location trying to kill my dwarves. Since I had two speardwarves with two wooden training weapons ready before I even build the first workshop I could fend him off with minor injuries.
A second option is taking one or two wardogs with you on embark. This saved me from a were-elephant once.
Since I opt for a main team of three miners, a smith/mechanic, a grower, a potasher, a carpenter and three masons (10 dwarves) I have a full squad of speardwarves training once I reach 25 dwarves, so about when the third to fourth migrand wave arrives.
I've gotten pretty paranoid since were-beasts got me multiple times in the first year after embarking. One even ripped my commander in full copper armor to pieces before getting mangled.
Since I'm not good at managing a lot of dwarves I dump about half of them in squads after I got my core team assembled.
EDIT: Traps don't seem to work against werebeasts I just read, since they avoid traps. Nothing a nice metal piercing with a long wooden extension can't fix, though.