I always like to put nohup at the front of the command and then & at the end. nohup will make sure the the command is completely finished even if you are logged out of ssh. The & sign runs the command in the background.
Using nohup also generates a nohup,out file where all output from the command is sent so you can keep up to date with how far it has got by using tail nohup.out.
Use screen, you'll feel more confident.
I'd still use cron though, and put the output to a file somewhere (perhaps have it e-mailed to you). The advantage is there is no human error where cron is involved.