That is if youre talking about road racing. If you're talking about mountain bike races, cross-country races are pack starts that stretch out pretty quickly due to the nature of the courses. There are races for all levels of riders. Check out local bike clubs which actually start their training programs now or soon depending on where you live. Take advantage of all the knowledge accumulated by the experienced riders who are happy to see new cyclists coming to the sport.
Speed is relative and relatively unimportant.
It all depends on so many variables. And, cycling is a sport where you get to test yourself against yourself. It's you against the clock and there are races of all lengths. Racing in a pack in a road race or criterium is a very scary and dangerous propositin and takes nerves of steel. That is if youre talking about road racing.