Allow me to definitively clear this up.
A couple of premises: There is general agreement on the process of germination. The seed is like an egg, containing the plant embryo and the "yolk" (food source). When the seed is exposed to sufficient moisture at sufficient temperature, enzymes are activated and germination begins. First with the growth of the radical (anchoring root), then the leaf emerges. Then comes "sprout and pout," a period when the seedling grows primary roots to take up water and nutrients to replace the diminishing "yolk" food source. It's also commonly accepted that plants acquire the majority of nutrient from those in soil solution.
As seedling roots are undeveloped and very shallow (top 1" of soil or less), most agronomists suggest that fertilization application (NPK) be made to supply increased amounts of nutrients in soil solution. [A few argue that no fertilization needs to be done (Mother Nature doesn't fertilize) presumably arguing that as the majority of active OM (either already present or from an OM topdressing) is in the top inch of soil, the mineralization of OM will supply the needed nutrients. There is some basis for this argument. In the mineralization of nitrogen, microbiology creates ammonium-N first which is later synthesized into to nitrate-N and some studies have shown that young plants take up and use a much greater percentage of ammonium-N than nitrate-N.] Some recommend that a starter be put down at seeding to avoid damage to the seedlings that might occur to the seedlings if fertilization is done shortly after sprouting. Others argue that a starter added at seeding will have washed/leached out of the top of the soil (seedling root zone) by the time the seedling needs it and that starter should be added later when it's "safe" to walk on the seedlings (after the second mow, or after 6 weeks, etc). Still others suggest that due to leaching (and the possible tie up of P, which can occur within days depending on soil chemistry), "spoon feeding" of fertilizer is the better method to maintain adequate soil solution nutrients.
The choice couldn't be more clear: pick your poison.
FWIW, I happen to be in ericgautier's camp. I've employed "spoon feeding" with good results, however I've also applied starter at seeding with a follow-up starter after the second mow and I can't say that I've seen any major difference in results.
Welcome to the forums, SNOWBOB11.