Here's the way it works in theory (and in fact how it worked for bitcoin):
0) initially there's no market, no trades, but there is a cost of producing the item. You might ask why anyone would make something that costs money but can't be sold - nerd enthusiasm
1) trade offers at specific prices are made. These were based on the cost to produce. Offers are not accepted yet. At this stage you could say the market exists.
2) the first trade offers match and execute. At this time the exchange rate is 'discovered' (at least the first guess at it anyway). Not sure if it was the first, but the most famous early price defining transaction for bitcoin was the trade of 2 family sized pizzas for 10000 bitcoins. The pizzas were priced in USD so the trade discovered the BTCUSD pair exchange rate. The 10000 was loosely based on electricity cost to produce the bitcoins.
In the current environment things work the same - people make offers and the market discovers the best price.
To the first part of your question, you can now see that the 'growth' is anywhere from undefined, thru infinity, down to some discovered value. It's pretty meaningless to apply it to early markets.
You ask if all coins are 'available at the introductory price' but the market price is dynamic and is determined by the demand and availability. Sometimes there are offers made to supply a fixed number of items at a specified exchange rate, but this is before a market is open.