Whilst there are no hard and fast rules when it comes to BCAA and glutamine intake (owing to individual variance), it is advisable that you take supplements in accordance with their specified guidelines. Generally speaking, it is best to take BCAA formulae before and after training (and during, depending on the product). For USN BCAA Power Punch, the directions are as follows: "Mix 2 heaped teaspoons (13g) into 500-750ml of cold water in your water bottle and shake well for 30 seconds. Individuals weighing 85kg and more should take 4 heaped teaspoons. Sip drink prior, during and after training/event."
If changing exercises and focusing on weak portions of the lifts themselves don’t improve things you may need to deload for 1-3 weeks. I don’t schedule deloads, I take them when I need them which is typically every 6-12 weeks. How long you take it for will depend on how long it takes you to feel mentally and physically refreshed and focused. For a deload I recommend doing your normal routine, but only using 60-70% of normal weights. So for if you would normally do 3 sets of 5 on squats with 300 lbs., I would recommend doing 180-210 lbs. on squats for 3 sets of 5.