Like currently there is gaps on most of major pairs in currencies, also gold, but I see its continuous up trends on them, that is ok , but I thought you meant trying to predict gap on Fridays before the market closes.
Depending on account size. Account of over a million dollar, I will not risk more than 5% if i seem too over sure and want to go for all, account of 100k and 500k, I have risked max 10% on both, and it was a good pay as I made over 37%.
You should always have target of what you can lose. You can allocate 1 to 3 percent of total account risk to all positions. The bigger the account, the lower the risk applied for me.
His opinion though lol. I'm a technical trader and do not trade the news and I'm fine keeping investors account safe rather than try to trade the news and get hit by spikes to stop loss, and market goes in your direction after that. It's better to be safe than sorry. 5 years track records...