O.k bro first off 1500i.u is way too much to be doing at one time. The half life of this drug is 4 hours or less, you'll be desensitizing your leydig receptors that way.
I recomend you do 500 max at one time. Begin doing 500 per day untill your testicles are fully hypertrophied. Then continue a weekend protocol of 250-500 iu.s Saturday and Sunday, each weekend. If you are doing deca, I advice you continue this protocol for 4-6 weeks after your last injection of deca, then begin post cycle therapy. Deca is a poor drug to recover from, as it continues to suppress your natural T production for up to 6 weeks after your last injection.