Gonna start trying for baby #2?

Okay so I'm 19 years old about to turn 20 and married to a wonderful man. I have a 4 year old step daughter and a 6 month old daughter. I want my children to be pretty close in age so starting in January I wanted to start trying for baby #2. My husband was all for it when we first talked about it but then he started seeing his daughter again (terrible custody battle) and he changed his mind to waiting about 5 years because it was "unfair to his oldest to have to share him with another sibling" 🙄 I personally don't think that would be up to her and in my opinion I don't think kids should be involved in making that type of decision, his ex has other children she does just fine with so she'll be okay if we have another one. Well I guess he's over that part now because he said last night that we can try for baby #2 whenever I want to he just thinks it'll be hard for me and doesn't want me to be to stressed out. Any advice on having 2 kids close in age or about having a step child jealous of their siblings?