That would be an issue that comes up because of size, which is why people usually use 1,500g as a benchmark for breeding size, but body porportions are also important. A long skinny girl might be 1,500g, but she's still too small and as you point out, more likely to get egg bound. A short, plump girl on the other hand might actually be ready well before 1,500g.

Just keep watching her, and tracking her growth, and of course feel free to add pics of her when the time comes closer. If she's looking good you'll have the reassurance from people here, and if she's not quite ready yet you know there will be people on here who will quite happily tell you about it .