as long as it had a needle and cap on , no problem. dunno how long exactly you could leave it there for but 2 days isnt an issue. i often preload a weeks worth of barrels at a time and ive never had any problem. so as long as you're careful with hygiene...
as long as your keeping it steryl , its good for a few weeks.. i asked the same question about preloading sryinges for a few weeks and the general consensus said it was fine.