"When can I consider more handling time?"

One of the least important factors in keeping your lizard healthy and gaining ANY sort of trust is to keep the handling down to little to nothing until they reach their bold stage and realize you haven't eaten them. May take a while, may not take such a long a while - every monitor is different.

The most important thing right now is to get it out of a fish tank and into an enclosure built specifically for him. Focus on that first and the rest will come.