Not easy to answer as it is dependant on having someone on the other side of your trade.
A stock with good volume at busy times will fill in milliseconds, a $1 low volume stock can take ages.
There isn't a direct answer to your question.
You can buy 100 shares in Intel at market as quick as it takes you to hit the buy button, but limit orders and low volume - even popular stock have slow periods take longer. The number of shares you wish to trade also has an effect.
If you are trying to factor this into your figures for paper trading, then slippage may be the more important issue. I may want to buy ICOS @ 21.18, but am filled at 21.20 depending on the number of shares on offer at that price and the others who are buying at the same time.
Have a look at the daily volume in the stocks you are thinking of, I generally don't like to trade anything less than 2 million a day in volume as I don't like to wait long for decent fills. Others are happy to trade less than this, it is just a matter of personal choice and allowances for slippage.