Not sure but assume that they would be in the system in a couple of hours for the pain relief bit...... anti inflamatory wise maybe a couple of days till results seen.... but thats just a guess!!
2 sachets? Isnt it normally meant to be 1 in a day?
Bute builds up in the system (hence why you dont just give it one day and thats it, you'd usually give them 1 a day for like 3 days then reduce to 1/2 a day etc.) so Ive been told can take 2 days before an effect can be seen. But I guess it depends if your using it for pain relief or just as an anti-inflammatory?