This is an almost unanswerable question. Far too many factors to consider;
Your original opiate tolerance
Whether or not you've done other opiates in the past 2 years
The biggest shot of heroin you've ever done
The purity of the heroin itself
and much more. I think it's safe to say that it's never a good idea to boot almost a gram of dope without testing a small amount of it first, but there is no possible way any person on this forum could tell you whether or not you will overdose from it. My recommendation, boot up about a 1/10th, see how it makes you feel and work your way up from there. Remember, you can always get higher, but you can't get lower.