trans bad???

ok my 95 monte carlo when i put it into drive and when it shifts from neutral to first around 15 mph it shifts but sometimes it shifts bad kinda hard but when it shifts after that its fine does this mean my tranny is gonna go out soon or what bc im about to put new struts on all 4 wheels of it and if the tranny is bad im gonna forget about the struts then any help please

thanks

explain....more detail..doe sit feel like it is slipping..did u check the fluid level, etc

fluids are good car does have a lot of miles but i mean it shifts when its suppose too. it shifts between 2500 3000 rpms but like if i go slow if shifts perfect but if i pick up the speed a little bit more it kinda rocks back a bit but after if shifts from neutral to first it shifts perfectly fine into other gears.