coz it was due to test last month, would it matter if i used it once then sent 4 testing?
coz i am going paintballing in 4 days!
A born date of 2004/06 does mean it has expired unless there are any additional test labels on the bottle.
It does matter in that the bottle is out of test and is illegal to be filled. Any site should refuse to fill, and if self fill is available the site should inspect your bottle before letting you fill. Either case results in you being refused to have the bottle filled.
You are better off borrowing a site bottle.
As this is a steel bottle I hope you got it cheaply as to be of any use you have to get the bottle tested, and to be worthwhile you need to try to avoid postage.
The preferred option is HPAC testing. Ask your local paintball site if they can sort something out, or hang onto the bottle until you can get to an HPAC attended event, you can then hand them the bottle and collect it by getting to a subsequent HPAC attended event. This would avoid postage.
Failing the above there is the option of dive shops arranging testing. Be very clear that you want to test a steel paintball bottle and they ought to be able to arrange testing at a similar cost.
The disadvantage of testing a steel bottle is the relative cost of the test to the cost of a new steel bottle at about £40, but the advantage is that a steel bottle can last forever if it is repeatedly tested and passes. A fibre bottle has a final use date so has a limited lifetime. Therefore steel bottles become cheaper and have a longer working life.