depends on your methods for the first 100 turns (marathon scale). Normally an IMP leader would like to REX the map out, so maybe yes. now please correct my calculation if i'm wrong: For marathon; settlers = 300 hammers turn:1 (4000BC), capital pop: 1 city tile on a plains hill : 2F, 2H, 1C work on plains/hill with forest: 3H for settler building, "food surplus+hammers" are counted. that makes 0F+5H. With imp trait, it makes 7.5 hammers. I think, it shoud be rounded down to 7. So 300/7= 42.85 = 43 turns! If it's 7.5, then 40 turns. WOV! That's very fast for 1pop capital. Normally, without IMP trait and plains/hill city, it would take75 turns! So, starting with settler shines at the first glance. But still waiting until making a decision where to settle the 2nd city, seems a more reasonable choice. Scout the area, check if there is any very important resource that you would never want to miss. Because before building your 2nd settler for 3rd city, that resource may already be lost to an AI or barb. Which resources can it be?Well, especially copper, horse, stone, marble; depending on your playstyle. that may take a few 10 turns to scout the area totally. Building a settler in turn 43 might be early as Sisiutil commented. So you have 2 choices here. 1) build a worker (24 turns in marathon, plains/hill capital) irrigate a corn tile. It makes 5 food! So it speeds up your settler building turn a little bit. But the main speeding up will be after you research bronze working, CHOP. So instead of turn 43, you can do it in turn 55-60. Still, incredibly fast, even faster than 75! Plus you will have a worker. 2) you can train units/build wonder until your capital pop reaches 2/3 or maybe 4.