The amount of time it takes is based on how many candles you do. Don't do more than 13 or 14. Candle lighting itself has no religious meaning and can be skipped altogether if you prefer.
You could do only 3 candles if you want it really short

Past(memory candle), present(all the guests), and future(Guest of Honor).
Remember a long candle lighting is a boring candle lighting.
Rules for a great candle lighting:
1. keep the total number to 14 or less (14 candles=20 min apx.)
2. keep your poems short! (about 4 lines)
3. pick up beat songs to be played when people are called up. "Wonderful World", by Luis Armstrong is a nice song, but if most of your songs are like this it will put everyone to sleep.
4. Do not have a course served during or directly before the candle lighting or no one will pay attention to your son or daughter b/c they will be too busy eating. If you child worked hard at the candle lighting then they deserve 100% of everyones attention.
5. If you have a memory candle (candle for the deceased) then you do it FIRST! It is a sad candle and you are trying to make the candle lighting fun and upbeat so you need to do this candle first or it will diminish the mood you have built up.
Thank You,
Eric Cutler